What mid ranges would be good to have a unique set(so that each disc is very different- like one that goes straight, one understable, one like the cobra that makes an s, etc)
I take it you have a VRoc and a Cobra? Between those two, you're probably set well for mids. If the Cobra is fading back on you and you want something decidedly understable, you'll need something drastically flippy at your distance. For Innova I'd recommend DX Stingray, Skeeter, Panther, or Kite (those last 3 are smaller diameter than your VRoc and Cobra though). A DX Aero is a wide diameter putter but it's basically a really slow, finesse midrange and a great disc to learn technique with too.
At your distances you'll get more benefit out of sticking with mids and putters for the vast majority of your throws but I think it's always good to keep a slow driver in the mix to learn how to keep the nose down. Innova makes a lot of great ones in DX: Gazelle, Cheetah, and Leopard from most overstable to least. Eagles (especially L molds) and Teebirds are a little faster but great too in DX, if they're too beefy at first a few trees will straighten them out in no time. Other really good, slow drivers: FD, JLS, Polaris LS, Relay, Signal, Seer, Jade, etc.