Up to date f2p guide

I am still not sure about plasma, she seems less and less useful to me, especially now that I am lvl 59.5 and still haven't unlocked Biggs...

Worst choice to start imo. She is still godo and usefull, but falls short to Biggs as a starter unit.

I am about to unlock ships, is there anything I should do before hand? Should I level up certain ships? Should I have certain chcaracters leveled? My pilots are JS, GS, both at high level/gear and CS, TFP, and RP all super low level. My ackbar is quite high level but my tarkin and windu are not.

You can't do anything beforehand since you have no access to ship shards. That being said - you have almost no flexibility here. Go with ships that have best/highest units. You can use 6 ships in fights, so you can't be choose now, unless you unlock additional units. Go same as with normal arena, try to get top10 and stay there. First few days buy only shards for your current ships. On 62lvl you get admiral ship challenge unlocked and you need 6 ships with 2* rating to enter it.

well i found this guide too late. any ideas for a good team? (dont stand a chance in arenas)
link to account --> https://swgoh.gg/u/dmaniac/

Say your prayers, bury your phone in the back yard , walk away and never look back. Can't give any reasonable advice since none exists. To put it into perspective - getting a good team woud probably take 1-2 weeks. Climbing to top100 probably around that as well. But in all honesty, you can't close gap between your opponents like that. Not those in top20, so it would probably still be problematic to even get into top50-100.
My best guess would be phasma (l), chewie, JC, GS, Lando.

My thinking is to farm Geo Solider in cantina store as with fleet I will be able to farm Biggs....does that seem the best way to go given my team structure?

You can farm Biggs in gw shop, fleet shop and in nodes, so go for gs.