Hey Elfwitch.
It's a slow morning at work so prepare for an essay in answer to your queries.
In addition to the above suggestions I also recommend getting Hero Designer software if you haven't already. It makes designing characters very easy.
With skills it's important to keep in mind that HERO has a very granulated system. There are no really big "catch all" skills. Of course it's possible to create them in the rules. HERO Designer even has a "Custom" skill button. Pick it, call the skill what you want and play it exactly as the equivalent skill in DND. But one of the benefits of HERO is that it plays differently to DnD. I'd use it that way. Of course I realise that your GM says how the campaign is actually run. If they want it to play just like DnD they can, it will work. But I'm working on the theory that the system has been chosen because a different play style is wanted.
Anyhoo...
For skill equivalents I use the following:
Bluff = Acting.
Diplomacy = Bribery, Bureaucratics, Conversation, High Society, Interrogation, Persuasion, Seduction, Trading. (Erm, I did say it is a more finely granulated system didn't I?

) These skills are generally used in the competitive, skill vs. skill fashion. I will say I don't think there's any need for Bribery and Trading. To my mind they do the same thing - facilitate a quid pro quo exchange.
Knowledge Skills are easy: define the branch of knowledge, buy the skill. So Knowledge Arcana (DnD) = Knowledge Skill Arcana (HERO.) One thing to consider is that Knowledge Skills can be as broad or as specific as you, the player, wants them to be. e.g.. KS:Arcana (DnD) covers all magic, stuff about dragons, inventing spells, etc. In HERO you could buy them all as separate skills*. What is implied by the rules set (but just implied AFAIK) is that a more specific skill will get more specific answers for the same level of success. e.g.. Make your KS:Arcana check spot on and your character knows "That's a dragon." Make your KS: Dragons roll spot on and your character knows "That's an Acid Drake. Swims and breathes acid, you know."
*Inventing spells must be bought as a separate skill: Inventor (Spells). At least according to RAW.
Languages can be bought at various levels of fluency from Basic to Idiomatic with literacy costing 1 more point on top of whatever level you can speak it at. There is the Linguist Skill Enhancer which makes any language you put points into effectively 1 higher. e.g.. Buy Orcish at basic (1 point) you actually get it at fluent (usually 2 points.) The Linguist ability costs 3 points. This will save you only 1 point initially but will save you more points going forward.
There are no direct equivalents for Intimidate or Sense Motive.
The way I would run Sense Motive by is simply giving certain types of information when a diplomacy skill is used. So in a Conversation vs. Conversation roll off, the winner gets a few hints about the loser based on degree of success and circumstance. Some of these hints may be about motives.
Intimidate is a simple Presence Attack. Anyone can make a Presence attack. It's a Zero Phase action. It takes no time. It is part of your other actions. So, frinstance, the big bad barbarian kicks in the door, charges across the room and sweeps her axe through an orc's neck and screams at the survivors (Amanda Plummer from Pulp Fiction style) "If any of you





move, I'll execute every






-







last one of you!" The effectiveness of your Presence Attack is based on your character's presence with modifiers up or down for things like surprise, violent actions, extremely violent actions, good or bad soliloquies, already being in combat and bunch of other things your GM will have on a list.
Elfwitch, you mentioned scrolls above. The easiest way to make a scroll is to buy a bunch of spells with limitations that represent the fact that they are only available because the character has taken the time to charge up some magic and store it.
So something like Variable Power Pool with limited charges (equal to however many scrolls the character has at one time); Fragile Obvious Accessible Focus (the actual physical parchment); Limited Power: Spells can only be changed back at base/in the lab/at the library. What all that means is your character has a few scrolls. Specific, pre-defined spells are on those scrolls. What is written on the scrolls can only be changed back at your necromancer's library (or equivalent place, like someone else's library.) In practical terms your scroll load is decided at the start of the adventure and then doesn't change until your character gets some down time.
In fact a bunch of scrolls works exactly like what is called a Gadget Pool in the Super Heroes genre. Gadget Pools are already defined in the main rule book (in 5th ed anyway. Probably also in 6th ed, but haven't actually read that one) so just have a look at them. The scrolls are just magical gadgets. Wands and so forth could also fit within this gadget pool but I would suggest a second, separate gadget pool for wands as there's enough difference (the number of charges) between DnD style wands and scrolls to warrant a second pool.
Using a Variable Power Pool (of which a gadget pool is a subset) requires a skill roll. In the case of your Scroll Pool this skill might be Scribe Scroll.
I will have to disagree with Nagol on one point: do NOT buy your scrolls as Independent Foci. You can, but DON'T. The character points spent on Independent Foci are gone gone gone once the scroll is used. XP in HERO is more valuable than XP in DnD.
Charnel Touch
Buy it as a Blast, no range (or a Hand Killing Attack, aka HKA) vs. Energy Defence or maybe NND (not versus Longevity.) NND is "No Normal Defence." It makes a power very expensive but also VERY effective except against targets with the defence in which case it has NO effect. Zero, zilch, nada. I would not buy the power "No END" unless your character is going to be using it all the time. In practical terms paying END for small - middling powers doesn't put much of a limitation on their use.
You mention your character becoming a lich as they go along. Cool. But it occurs to me you might be expecting certain benefits from that state that don't equate in HERO terms. The, um, dis-join that first occurred was the undead immunity to Mind Control. HERO doesn't do immunities (with the except of NND as explained above.) One can buy a hell of a lot of defence making one immune for all practical purposes. But this is expensive. Odds are you will simply buy a chunk of Mental Defence and make do with that and your character's innate high Ego.
When going from DnD to HERO I'd take the opportunity to avoid certain DnD conceits.
One that I like is wizards can (and if they have any sense and want to live long happy healthy lives, should) do is wear armour.
I'd also chat with the GM and players and see if they want to avoid Vancian casting entirely. Vancian is a bit of a shoe horn effort for HERO.
Something that happens in HERO is that it's possible for spell casters to wind up paying many points for something a warrior type can do for free - to whit cause damage. For instance a sword does 1d6+1 damage. A warrior gets a sword for money, not character points. A wizard will have to pay 20 points for a spell that does 1d6+1 damage. This cost is then brought down by limitations like incantations, gestures and material components but it is never reduced to 0. Power Pools also effect exactly how this is going to work. Depending on how the GM wants magic to work this can make a wizard type much less effective in straight up damage dealing. In this case I recommend focussing those things warriors can't do, like summoning the undead or laying down walls of fog or fire etc. Area of effect attacks are another thing.
I'm about out of ideas at the moment but if you have any questions please feel free to ask. (my afternoon is looking slow too.)
Cheers.
edited for typos.