If you were going with 1st level characters, I'd probably just use the example builds in the PHB.
For higher level, it looks like those rules would be OK, although you might want to give them more powers (maybe have them pick one, then pick another for them?) A level 10 NPC has one at-will, one encounter, one daily, and one utility power, so it feels like 5 of them as PCs up against a suggested lvl 10 encounter would be a lot harder because they have so few options.
What I'd do if I were you is do what you're thinking, but then use the chart in the PHB to determine how many powers they should have at that level. That, and give them healing surges "by the book" for PCs by class. That'd probably be workable. (I think you can leave feats out entirely and the game still works, especially for a quickstart type of game.)
You could get crazy with it and have them just pick one of each type of power initially, then after you've been playing a bit, they could choose to use another power (that they had, it just wasn't on their sheet yet.) They'd then write that down on the sheet and mark it as expended. That way you guys could try out some of the neat powers without having too many choices to start with.