I am fairly read up on the enneagram. The enneagram basically dictates your behavior. Socionics is the tool, enneagram is how the tool is used. It's separate. So don't think that the two are linked.

This is a great site for the enneagram. The descriptions are to the point and very good. Here is the type 4 description to start off with- http://www.9types.com/descr/4/

From there at the top you'll see that you can access other type's profiles. Also a little bit below that you will see something called "Diagrams", be sure to check those out too, those basically say what "loops" the said enneagram type can get in.

As a 4w3 or 4w5, you will have mostly type 4 traits but also relate to some type 3 or 5 traits. They don't have to be all of the 5 or 3 traits, but just some. It's also possible to have balanced wings, but that doesn't happen too often and you usually lean toward one wing or the other.

Good luck, ask me anything in a PM you want to about enneagram if you're confused. Cheers.

EDIT: I also noticed you use AIM, so feel free to message me over that if you're confused as well.