Sorry about that. Part of the confusion is that you have added some changes, and changed some goals, and we were cross posting.
Okay, I think I understand your system as it currently stands. It is based around the concept that what you choose early is the most important influence to you. No problem.
This does not match your initial desire to have your new multiclassing choice reflect your skill improvements. (Which if fine, just noting it.)
So, everyone gets the same 'skill points' except at 1st level. (except the Rogue, who gets double)
Intelligence is much much much less important. (You may want to bump it to +3 per bonus)
The human bonus is likewise much less important. (as in, close to zero--you should at least bump it up to +2-3 instead of +1)
What class you pick at first level is *much* more important than it used to be.
First level Rogue, picks up UMD, search, disable device, tumble, etc. Then switches to fighter for then on.... He can either spend 3 each, and get these as supreme skills as a fighter. Or he can spend 1 on it, and spend 2 more as he levels up to get them to supreme.
This could also play havoc with getting into prestige classes.
System seems okay, in some ways I like it better. I don't see it being any less 'difficult' or 'confusing'.
I would change the wording a bit:
"You may use your skill points to select any skill at whatever step"
1 skill point

oor
2 skill point:average
3 skill point:good
4 skill point:supreme (??...See Below)
"If the skill you select is listed as a class skill, it gets a one step boost if selected at first level. [Note: there is no level past supreme, thus it does no good to spend more than 3 points on a class skill]"
I see this being a bit easier for creating high level characters, but I see it being no easier for leveling up, and in some ways harder. you will still need to check a chart every level, see which ones have changed, and update your sheet. Or at leaset update what P/A/G/S equal at your new level. You need to change your rating on one every other level.
While that is not difficult, neither is adding 1 to a number.
Of course, you have effectively gotten rid of the human bonus, the intellegence bonus, and class skills. So that will simplify things.
You have also greatly increased the skill ranks available to certain classes, and thus reduced the rogues relative advantage in those areas.
Questions.
Fighter puts 1 point into climb (Class) at first level. Is now at 'good'. He can put 2 more points at level 2&4 to get it to Supreme.
Fighter puts 1 point into diplomacy (Cross class) at first level. It is at 'poor'. He put 3 points in at level 2&4 to get it to 'Good'. Can he put another in at 6th to get it to 'supreme'?
Fighter waits until 2nd level to put a point into Climb (initially a class now a cross class) and gets it at 'poor'. He can put 2 more points in at 4&6 to get it to 'good'. Can he put another point in at 8th to get 'supreme'?
Fighter waits until 2nd level to put a point into diplomacy (cross class) and gets it at 'poor'. He can put 2 more points in at 4&6 to get it to 'good'. Can he put another point in at 8th to get 'supreme'?
At first level, can fighter put 4 points into diplomacy to get it at 'supreme'?
If any skill can be stepped to 'supreme' than it makes class/crossclass less important; but if you can't, it adds more record keeping.
Since you are after a more 'powerful' skill system, and simpler. I would say:
Lower some of the initial skill levels a bit (like make the 10's into 7-8, etc. keep the rogue at 16) .
Double the Int bonus, and triple the human bonus.
Only allow players to pay 3 points per skill at first level. This means class skills can get to 'supreme', but cross class only to 'good'. But then ignore any difference. If they want to take cross class up to supreme at level 2-4-6-etc., let them.
I would like the int bonus to impact past first level, but I don't see an easy way with this method.