I'm assuming you're a low gp account since your doing easy mode. I'll try answer your questions the best I can.
1. No way other then to continue getting gear. Idk how well your focus is but try to gear 1 squad at a time. Get them to the benchmark you want then move one. G12-R5 is decent benchmark for low gp accounts.
2. Don't level up every toon you get off the bat. 1 toon cost about 6m credits to level from 1-85 not including gear and modding.
3. Bossk lead BH can work but it maybe dicey. Getting contract and mando to disintegrate GI or Ninth sister to reach GI. Third sister will revive after the first shot.
4. Keep chugging along untill you can move up to normal mode. The rewards in normal are much better. Remember this. The last crate of easy is pretty the same as first box in normal. The rewards only get better
