Ok so Ive made a Teifling ranger, with racial bite, ranger natural weapon claws.
Can I then take Two Weapon Fighting, Improved two weapon fighting and get a claw claw main, claw claw off hand? With then only one bite.
Nope. Natural attacks don't work that way. They are off in their own little world, almost entirely distinct from regular weapons.
Basically- you get bite/claw/claw. All full str/power attack, all at full BAB. That is the trade off- you can get all the natural attacks out, and they allhit at full power (assuming they are primary attacks), but you don't get iteratives.
I wouldn't worry too much. Bite/claw/claw dominates full attacks for levels 1-10 as a full BAB class. You may want to look for magic items and such to get more natural attacks after that though.
So when I build this guy, 20pt buy, just dont worry about Dex at all?
What about when hasted? What gets the extra attack?
When hasted, you get a single extra attack. From whatever. Your choice.
This is true whether it is nautral attacks, 2 handed attacks, or when using 2 daggers.
Haste is a bit better for 2 handers because of that, since their extra attack is at x1.5 str and power attack.
EDIT- oh, and with point buy- you aren't going around in heavy armor (in fact, I think your claws turn off in heavy armor, since that is part of the combat style thing), so you probably want 'some' dex.
I can't judge what to do for your point buy, since I don't know what bloodline you are using (heavily influences stats), but I can tell you this: 12 wis is fine. More can be better, but 12 lets you cast your spells throuhg level 10 (and by then, you should have a +2 wis headband anyway- so no worries about casting at all).
Don't sacrifice your physical stats for casting. You aren't really that much of a caster, so just go with melee focused stats- str for attack/damage (the main stat to focus on), dex for AC/initiative, and con for health. If I had to take a crack at stats, then for basic tiefling, the stats should be about:
STR: 17 DEX: 14 (12) CON: 14 INT: 10 (8) WIS: 12 CHA: 8 (10)
And if you use the demon bloodline (which has +2 str/+2 cha/-2 int)
STR: 18 (16) DEX: 14 CON: 14 INT: 10 (12) WIS: 12 CHA: 9 (7)