Set Aside - racial classes and racial level limits. Why, these are mechanics mainly to give the human/demi-human mixes a certain default flavor. You can encourage that flavor without hard limits and get most of the bang.
Set Aside - highly tactical game widgets. This is counter to the spirt of the "strategic" aspect of RC play, at least in practice. And besides, we haven't had a D&D version that really went after strategic play since 1E.
Level and class limits in early editions are crap. I was very glad when D&D finally let that die. I do wonder what game you have been playing if there hasn't been strategic play since 1E. Maybe we aren't using the same meaning here, but there was a heckuva lotta strategy and tactics in my 3E group and in the Dark Sun 4E game I was playing in recently.
Ah. So your 4-3-2 could actually cast 9-0-0 in a day if it wanted, then? This isn't something I do - you can't change slot levels like that.
I would say the easiest route is just a simple spell point system. Each spell per day gives you one spell point per level of spell. So 4/3/2 for L1/2/3 spells would mean (4*1)+(3*2)+(2*3)=16. If you want to cast 16 magic missles go for it. 5 fireballs will do a lot of damage and probably save your butt, but then you only have 1 1st level spell left. This method also would mean you know all the spells in your personal spellbook and there is no fire and forget. This may slide away from the original intention, but it makes things easier for the players.
Also, another gem from 1e: x.p. for a successfully avoided encounter are to be given as if the encounter was defeated (the risk must be known and steps must be taken to avoid it; getting past an opponent you never know about doesn't count). Here's where your Thieves and sneaks can shine!
Isn't that rule back again in 4E? can't remember if it was a part of 3E, but I'm fairly sure that is standard in 4E now.