I'll try to address this as best I can...
I heavily advice farming baze from shipments ONLY if you are top 5 in arena every day, or plan on buying crystals. If not, get STH because he will be much faster anyways. The rebels I recommend getting to 7* for the Emperor event are Wedge (cantina), Biggs (GW), Lando (cantina), then 2 of STH, AA, or Leia (all arena shipments).
Also, regarding who to farm, I would choose one and stick with them to the end. It does no good to have several half-finished characters lying around. And yes, many of those are from cantina, but you'll have to make the decision if you want to go for the emperor, go for raids, or go for arena (which is likely a combo of some of those characters). TFP and B2 are good (though I despise that trash heap B2), but personally I'd take wedge and lando to 7 first, then decide if you want to finish off Aayla or Kylo.
Oh god no never buy training droids. The time will come when you have enough to take every character in the game to max lvl, but you'll severely lack the credits to do so. Just be patient on that front.
As for dark side characters, again, just give it time to develop. There's no rush to get anyone in particular immediately, and over time you can farm who you like and theory craft a fun team as a goal to work toward.
And no, don't give a lick of attention to ships at this time. Just use what ships you have with what pilots you have and deal with that much later. Arena is far and above the most important for the daily crystal income, so make sure you prioritize that over anything else. Then probably raids, then special events, then faction events/mods, then after everything else, ships.
Hope that helps, and feel free to ask any more questions you have!
EDIT: Actually, I think the first thing you need to do is hone your attention on just one or two squads. It seems that you're trying to accomplish too many things at once and getting lost along the way. Just chose a goal you want to hit first (i.e. Emperor, Yoda, raids, high arena placement, etc) and focus on that. Then once you are satisfactory in that goal, move on to the next.
