Hey there!
I don't know how much we can help you with individual mods fitting together or not - best bet if you can't get it to work is to ask in the appropriate 'main' threads (for instance over at BIF). That said, I know that XAM is a total conversion mod, whereas FFN isn't, although FFN changes all the same things XAM does (including AI, animations, weapons, weapon dispersion etc.). It might work or it might not - it all depends in which order you put them in the -mod= line.
-nosplash is just another thing you can add to the starting line, just like -mod = ; it just removes all the starting splashes (BIS logo etc.) and makes the game start up a bit faster (in theory).
Wolfrug out.