Don't worry about it looking uneven, some of the spinners you're up against will soon 're-model' it

As for the cells I'd discharge them and then trickle charge them nice and slowly the night before the event. Then on the morning (at the event) give them a fast charge until they're brimming!
Then after each fight (once they've cooled down, do not charge hot) give them another fast charge.

You get some pretty decent gaps between qualifier fights. They should last fine, plus I'll bring you those spares (they're not made into packs though, so bring some gaffer tape!)

ps. Just looked through the photos, I like the way the armour moves with the lifting mech. Reminds me of a turtle! Pulling it's head in.