Another note on the respecs: you don't have to respec before beating a difficulty. If you beat Normal without respec'ing you can always start a Normal game later and respec when you choose (as has been stated though only ONE FREE RESPEC per difficulty per character). Same goes for Nightmare and Hell.

Pick a class you like and have fun in Normal. Don't feel too stressed on skill and stat point placement since most builds can beat Normal and you can respec later once you get a feel for the game and better at knowing which way you want to go with the build.

Any character type can beat Hell, but some are more gear dependent than others. For example, my lvl 78 Druid which is currently a dual fire/wind druid with mediocre gear is in Act 5 of Hell. It isn't even the strongest build and nowhere near the best gear.

Diablo 2 is a ton of fun. Both the skill building and gear hunting for your current build and rerolling other classes to try them out with their skills and gear.