To answer your question about troop, no time is a bad time to level them, but I recommend having a plan. Since events limit the troops you can use to 2* for rare, 3* for epic, and 4* for legendary, I recommend leveling a few of each. It takes a little longer, but Tripp’s do make an impact. I and leveling 2 each of 2*, 2 each of 3* and one 4* for each color troop right now. I do not increase my barracks level until they are all maxed out. I recommend you using troops that increase damage for 2* and 3*, for 4* you want to focus mostly on mana increasing troops.
You can lock your troops, just like your heroes, so you do not throw away troops that you are using. If you do not have a 4* troop, then I suggest leveling a third 3* troop.
If you have 1 4* troop, 2 3* troops, and 2 2* troops you will at least have a leveled troop if you want to color stack in the future, up to a mono colored team.
That is just my strategy, I’m sure other people have different ones and I would be happy to hear them.