When you take land, and start your own faction, you get to choose from which country shall you use the troop tree, any of them should be available!
YES!!!
When you start a faction, you get to write a nobles' title for your companions if you take them as vassals, so it won't just be " Lord ", but for example " General " / " Vojvoda " ( Grand Duke in Montenegrin/Serbian/South-Slavic <w/ exception for Macedon and Slovene> etc etc. For easier starting of factions, as many will like to do so.
You've gotten sneaky. 
It's one of the South-Slavic languages it originally comes from, probably Macedonian if I am right ( Voivode ), there's an old song about the Serbian ruler from the Napoleonic era - Karageorge
Sedam sati judara
Bejograd se jotvara
Jotvara ga Karađorđe
Ju njega da dojđe
Karađorđe na čelo
A za njim sve Vojvode
A za njim sve Vojvode
Stupaju Bejograde
-----Translation from the original language, which I don't know which one it is, could be ANY south-slavic <From Bulgaria and Macedonia to Slovenia, including everything between them>
Seven o'clock hits
Belgrade opens
Opened by Karageorge it is
So he can come into it
Karageorge is on the head (of the army)
And behind him his Dukes ( Vojvodas )
And behind him his Dukes
Step into Belgrade
It's about the Belgrade liberation of 1805....
It'll end up with him writing a sentence in a Mystic way OfN wriTing likE this. hough this certainly is Not Even close to beinG Really snkIky, No? 
If you haven't noticed, all my posts are 100% gramatically correct, I'd NEVER EVER get so low to write like that with capital letters, I'd rather say - Montenegro/in/[...whatnot...] than type like that, it'd be a disgrace!

Edit : Found two versions of the song
http://www.youtube.com/watch?v=ia_PQwjPk8Yhttp://www.youtube.com/watch?v=uAK4Ewa7G6w&feature=relatedI'd suggest that either one ( better the 2nd, it's more realistic for that era! ) of them is inserted, as they're simply....beautifull.... I say this even though I know a lot into south-Slavic classics and traditions, including music, this is one of the best songs honestly!