[Ask] Have a couple questions regarding trophy grinding and upgrading

Currently TH9 with King going to 21 and Queen going to 18. I'm also currently Masters 2. Is it worth me upgrading both heroes at the same time? (don't currently war) I kind of want to hit champions for the 2000 gems, is it possible for me to hit champions without using heroes or dark exilir, if not should I drop down to crystal or something so I can just loot? (currently a lot of TH10s with good loot but can't even 1 star without using DE). Last question being about walls, how important is it for me to get my walls to lv 10, there almost all 9? Thinking of just upgrading walls until my heroes are done then moving up