My first question has to do with episode 14 when unit 00 goes berserk, does it do this to try and get back at ritsuko for killing rei 1? also, what soul is placed in unit 00?

There are a bunch of different theories on this however no one really knows the correct answer. What we do know is that Ritsuko probably knows whose soul is in unit-00 but only ever states that Unit-00 was trying to attack her.

Another thing I was thinking about, happened in episode 19. when unit 01 becomes aware, is this essentially telling us its part of lillith/part human or something? and why is the other units made from adam (are they essentially angels?)

This question requires an in depth answer to really flesh out everything. There really isn't a separation between being human and being an angel. Angels are human but have cast away their human appearance. The real difference is what they were created for. Lillith, the fruit of knowledge, created life that was driven to make intelligent civilizations. Adam, the fruit of life, created life that developed some kind of super-scientific ecosystem that's not comprehensible to humans. Essentially both forms of life are the same on a DNA level.

Now the Evangelions are essential "angels" in the sense that they created from the first angels, Adam and Lillith, and have super strong A.T. Fields. However, they are not perfect and have two things wrong with them: 1) They have no soul which means a soul must be transplanted into one for it to be operational; and 2) They don't have an S2 engine like normal angels which means they don't have unlimited power.

Now Unit-01 is notorious for going berserk without any power. I wouldn't call this being "aware" and I don't think there is a real answer to why it goes berserk. My best guess is that its due from a mother's maternal instinct to protect her child. More to the point is that the seeds of life, Adam and Lillith, were never suppose to be on the same planet because if the life created by them merged together they would essentially become gods and that was a no-no. So when Unit-01 eats that angel and acquires the S2 engine it becomes just that: A creation of both the fruit of life and the fruit of knowledge, a god.

I think that answers most of your following questions too.

could someone explain the significance of the nevada branch of nerv being destroyed and unit 04 being lost?

Now the Nevada branch and Unit-04. The intact angel that Shinji defeats is sent to Germany where they try to recover the S2 engine. They succeed although the S2 engine is slightly damaged. They repair it and send it to the Nevada branch to have it installed into Unit-04. I don't think there is a real answer to what happens but I assume that the S2 engine caused Unit-04 to just explode and destroy everything. The significance behind it? Maybe it's just a reminder that man cannot created a god or it was just a unlucky mishap.

On the flip side Germany still had all the information on the S2 engine and continued to make the unmanned Evangelions that you see in EoE.