Personally output wise id suggest healers should be 20% less than dps, just like tanks being 20% less. So tanks/healers do 40% of the party's damage and dps doing 60% (each individual t/h does 10% each dps does 12%)

As for rotations thats easy.

Sch can be dot mage once more. Broil, miasma, miasma 2, bio, shadowflare, bane, art of slap, fester, energy drain

Whm can have a version of its stolen self buffing. An elemental combo that has water/stone/aero and has a burst that deals light damage.

Astro can have a 2 or 3 part proc system and an action that triggers from playing cards. This action starts off a little mudra esque thing where you read the enemy's fate and do a damaging move to them.

Sage gets a couple of changes to its existing one button dps mechanics, then gets to have more addersting generators and a combo. You can use eukrasia to make something akin to hw/sb dark arts. The effects will be various debuffs on the target.