Don't bother with the Tap Damage upgrade. Your Warrior/Paladin becomes way stronger than your autoclicking can get. You'll try and max each of his slots (especially glove and shield). The only upgrade you need is Tap Heal, and set your autoclicker on the Warrior when you farm. As long as he doesn't get one shotted, you'll be able to keep him fully healed while he defeats the enemies.
Bullet + Powder Cannon + Sonic Burst. Upgrade them all evenly until Bullet is maxed, then max Powder Cannon, then get Sonic Burst to lvl 8ish, and add in another Sonic until 8ish. Repeat until you have all 4 slots filled, then upgrade them to max level.
Some attacks that hit more than one person don't give full xp. For example, if I hit 2 people with massive shot I only get ~5xp. However, after the turn is over, the top properly registers at 104 damage done. The 5xp received is never fixed to 10xp at any point in the match. I know there are atleast a few other weapons that do this too.
here's a suggestion: how about maps that have environmental strategies besides the earthquake. Like a tornado barrels through random parts of the map, and whoever gets his loses points/xp...
not by best of the orbit challenge level, but not bad either. i think my best was about 100revs and was more circular:
||R|||-138,154,145,179,46,165,p,0,0,0,1,-137,154,145,245,31,5,p,0,0,0,1,-137,155,145,173,162,224,p,0,0,0,1|-214.6|191.85|-303.3|70.9||