The person scribing the scroll pays the XP cost and the price of the scroll increases by 5 gp per XP point.I am pretty sure that if their is an xp cost in a scroll then it is still required (and then pulled from) the caster at the time of casting.
DMG, page 287: "If casting the spell would reduce the caster’s XP total, she pays the cost upon beginning the scroll in addition to the XP cost for making the scroll itself."On the other hand I must say that I am pretty sure that if their is an xp cost in a scroll then it is still required (and then pulled from) the caster at the time of casting. Since a scroll is just an activation away from being completed, I am pretty sure this is how it works.
Any of the high value but limited application spells are handy on a scroll. Things like Cure disease, Neutralise poison, Restoration, Zone of Truth, Locate object and so on. In other words, spells that are awesomely useful but only get used once/3 months or so, even if you always memorise them. An added condition for scroll spells is that you normally need a full round to use them (minimum). Put spells that you would commonly use in non-combat situations or to recover from combat effects.
I also strongly strongly recommend a Heal spell or other Cure Level Appropriate Wounds as an emergency backstop. This one should be given to the Rogue, or someone with massive UMD skills in case you get taken down. This goes double if you are the only effective healer in the group.
Magic Circle against Bad Stuff, Water Breathing, Freedom of Movement, Knight's Move, Mass Resist Energy etc should be memorised. If and when you need these ones you need 'em in a big hurry.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.