1) Allow Horadrim Teleport from Elder of Tristram in Lich form
2) Allow Chilling Armor from Scourgelord's Girdle in Lich form
3) (Perhaps) Allow Corpse Explosion in Lich form
At the moment 90% of summoners will use Shrieking Lich helm, and if you have max summons but need to switch from Skeletal Lich to teleport, re-apply chilling armor, or deal damage, you lose 2-4 skeletons and archers because of lost skill bonuses from faster cast rate on the helmet. Also the stun difference between Horadrim Teleport and regular Teleport is not so overpowered that you shouldn't be able to cast while in Lich form.
4) Remove the display of auras on skeletons/revives to help with lag
Removing the display of auras, NOT the effect, would help with lag when you have 60 summons with 10 other players at inferno cows.
5) Put a limit on the amount of Revives in exchange for slightly increasing duration, also helps lag
This is not a crucial suggestion but it could still help with lag and adding a few seconds to revive duration would be nice.
6) Refer to this thread by nedamettin for Golem discussion http://annihilus.net/showthread.php?t=11066
In short, using Perfect Gem/Skull with Iron Golem for different benefits, Golems having more health and damage, etc.
7a) When teleporting in an area with disabled teleports, recall all minions/mercenary to players position
7b) Roughly control the direction of your minions with a spell similar to Attract curse