Am I allowed to make a Jedi who has fallen and embraced the Dark Side in order to defeat the Sith? Can I make him a dual-wielder?

Do new Padawan characters even get to start with lightsabers?
And how did Sandis get the Jedi Padawan AND mando ranks? I thought you couldn't be both. They are different factions and one is a non-force user rank. Am I missing something?
Speaking of mandos, if I made a non-force user would I be able to make a Mandalorian bounty hunter or something cool like that, or are characters somewhat restricted at first?