1) What is the best class of stim currently out there? Something's got to be better than nano-class stims (lvl 52) but I can't find the schematics for anything else.
2) Where do you get schematics for level 55 stuff, like lvl 55 augs? Also, is there craftable lvl 55 gear? I'm not seeing these schems at either the trainer or on the GTN.
The level 52 stims are the best currently. You can get the reusable version, but that is slightly worse than the straight crafted one (Prototype Nanotech).
As for high end augments- just craft the new augments from slicing missions and RE them to learn new patterns. For craftable level 55 gear, well, it really depends because I'm pretty sure you can only craft 54 gear.