I'll just write out the answers as I read through it to not make a quote wall (I made that mistake in the ragin' debate earlier)
While there are no direct limitations (yes, you can be an evil cleric/paladin) you should discuss it with your DM to make it work - if you're going to be an evil cleric to a good god (or a good cleric to an evil god) you can expect the god to stop giving you powers each morning - which might lead to interesting stories of where else you can gain power and at what cost.
Leveling up increases your chance to hit through proficiency bonus (+2 for lvl 1-4, +3 for lvl 5-8, +4 for 9-12, +5 for 13-16 and +6 for 17-20). Prof. bonus affects your chance to hit with weapons you're proficient with, spell to hit modifier and spell save DC (directly, so it's +1 to hit every 4 levels).
Yes, the wizard and fighter have the same chance to hit with a weapon if they are both proficient in using it. The thing is, the wizard is much better off casting a cantrip since it will scale with his level while a fighter can do several attacks as part of his attack action as he levels up.
I think rangers have some fighting companion type of thing and pretty much everyone can have a pet animals.
Fighters get more API (ability point improvements) compared to all other classes. These can be used to give +2 to stats (any way you see fit) or take a feat (which are quite strong most of the time).
Unfortunately most people will say that stocking up on supplies needed to camp outside is "not fun" and thus I don't think that's a good solution. I'd much rather see story driven reasons why you shouldn't rest all the time though I feel like you'll end up just like BG 1&2... long rest, long rest, long rest... hey, at least the nostalgia folks will be happy, right?
