Hi there!
First off, did you read through the characters, classes and such in the NWN2 walkthrough section? I would start there.
About builds, you can make those builds you mentioned in this game it just takes some planning and familiarization with all the feats and rules to do it right. All you can do to this end is to read the specs on the feats and spells and skills and decide what you like then build a character around that. I usually do this first then think about what feats/skills/spells I thought were cool or fun then went from there.
There are MANY good character builds that I could recommend, but there are so many choices you would have to pick a style to even begin to narrow it down.
IMO, the fighter/wizard/eldritch knight build is by far the most powerful and fun to play. You can fight *almost* as well as a pure fighter in melee AND cast up through level nine spells

Too powerful, for me, so I played a bit more challenging builds.
My two favorites so far are a dual-wielding warlock/rogue and a greatsword wielding evil bard/blackguard.
I found that if you do most of the side quests you can make level 20 with a 1 level adjusted race and 19 with a 2 level adjusted race. I read where one person claimed to make it to 20 with the latter, but I haven't really tried myself.
That's the tricky thing about this game, it takes quite a bit of time learning all the in's and out's but you can play a wide variety of characters and play styles that it's well worth it. And yes, there is influence, and undead, and summoning spells (oh my!).