@Not Fishing Sadly Dwarves do not exist. Well, they
could exist, but they'd be very much semi-legendary beings that almost no man has ever seen, and deliberately hide their existence from humans. Unless you mean a Tyrion Lannister-style dwarf. As in, a human with a growth defect. I can see that working and the effect would be more-or-less the same to playing an actual Dwarf. To playing a real dwarf I have to say no, but to playing a growth-defect dwarf, that's quite alright.
What Tribe or faction have you got in mind?
As for the Pirate Path / Baltian privateers, i'd say 12 ships, and approx 1000 men. There was another guy going to play as Eodaen mercenaries, but i've not seen him since the interest check.
Don't worry about background freedom. Go wild writing the backstory, and if some of the things break the lore i'll talk to you about it over PM. Add as much flare as you wish (so long it doesn't become a Gary Stu).