1. Race: Are there any mods that bring back the scrapped MoO2 races? So far I have just found a Mrrshan mod (of which I don't know if it works with the current version) as far as 1 or 2 threads of one starting to create a elerian mod which sadly does not was finished (or at least it seems to be).
Right now my gaming experience ends at the race selection with a "Oh god WHYY??!!" and click exit button ;)
2: Resolution: Is it somehow possible to play it that way? From the few info I saw the 1024x from tropical seems to be the best right now.

Unfortunately, I can't think of any race mods that are up-to-date. The Guardian of Orion website used to be the best source for MOO3 mods, but it's seems to be heavily out of date now, and the last 2 (major) mods I grabbed off there were completely broken.
As for the resolution, the game was (sadly) only designed to play in full-screen 800x600. There are some mods that hack the UI in order to technically give you 1024x768 and windowed mode, but (with no offense to the modders) it's a clunky work-around. What they did was move the UI from the bottom of the screen to the side, exposing parts of the maps that would otherwise have been obscured. However, that extra space at the bottom doesn't register mouse-clicks. This results in a lot of moments where you are clicking on a system or ship in the bottom 1/4 of the screen and wondering why the game isn't responding!

Thanks for the answer :)
Yeah, I'm sure the modders did their best considering the "accessebility" (that even a word?) of MoO3. Now all hope lies in that one of the rights holding bean counters suddenly gets interested in what they are working with and sells the licence to Stardock so that they can make a MoO3 V2 (and lets imagine MoO3 never happend ;) ) *sigh*