So i also assume that you cannot choose traits that you didn't choose back in previous levels?
Such as at level 2, i only have 5 or so NEW traits to choose, and not the ones back from when i was in the Doc's room. ie, i couldn't choose "Small frame" at level 2 as it was only available back when i was in the Docs room.
Is this correct? Thus each level up i have a 1 shot chance at choosing the traits available at that time?
Traits can only be picked when you're creating a character, and tend to have positive and negative effects to balance each other out. They're just aspects of your character, like "Four Eyes," which gives you a -1 to Per when you're not wearing glasses and a +1 when you are.
Perks are purely bonuses, and you can always pick any perk from any level once it's available (ie when all the pre-reqs are met). So you can pick a level 2 perk at level 28, if you want, so long as you meet its other requirements.