Alright, I am quite new to modding and half of the time I don't know what the fu...nk I am doing.

Look http://img225.imageshack.us/img225/2048/wrye.png

Question 1: The yellow mods are in some kind of conflict with each other, right? The green ones are doing fine?

Question 2: Since the "improved series" seems to improve the same stuff Qarl's already improved, do I need it? Is the "improved series" better looking or what?

Question 3: Is it possible to say what I am looking at, in my game right now? Does the game use Qarl's textures overall and if there is a "improved" texture, it doesn't use Qarl's and uses the "improved" version? Is that right? Or how would Wrye Bash operate with my setup? I assume the list represents the Load order (from top-first to bottom-last).

You're new to modding, but you've taken the time to learn to use Wrye Bash and BAIN. I'm impressed, well done.

Yes, yellow means that some files within that mod are being overwritten by a mod further down the list. Usually that's not a bad thing though. In the case of the "Improved" series, it's a matter of what you prefer. For example, one package improves the building doors, however so does Qarl's. Whatever mod is lower down on the list is what will be shown. So if you have:

Qarl's Texture Pack III (Order: 8)
Improved Trees and Doors (Order: 9)

Then you'll get Qarl's new textures for everything, however the new trees and doors from the Improved mod. Say you do it the other way round:

Improved Trees and Doors (Order: 8)
Qarl's Texture Pack III (Order: 9)

Then you'll get Qarl's new textures for everything, including the doors, however you'll still get the new trees from the Improved mod. Whichever order you choose in this case is a matter of opinion. You can see what files conflict by checking the window in the top right.

On occasion, install order will matter. For example, if you install Mod A, you have to have Mod A's Patch below Mod A, in order for the patch to overwrite the original files. In these cases it's pretty obvious on the order however.

Final point, if you re-order the packages, right click on the sorter bar and click "Anneal All". This re-orders the resources internally so it reflects the new order specified in your list.

Hope that helps!