Retopology and Skeleton rig for game character in unity

I'm trying to get a character/model i've created in Oculus Medium into a Unity VR social game (VRChat) I have zero experience with Blender or any similar programs, and no idea how to reduce it down for a game engine. I'm just looking for someone with the know how to do a retopo, add textures and put a skeleton in my character for use as an avatar ingame. This'll likely sound outrageous but the model has about 7.5million faces and i need it under 20k, (10k would be better of course).. The model consists of 12 or 13 layers in Medium and i've no idea how to work with them in Blender.. Medium also spits out a bunch of textures to go with, but again i'm clueless about what to do with them.. This is my first time hiring anybody on a site like this so feel free to ask questions if i'm leaving anything out, i've tried compressing the original file that is 940mb but the best i can get it down to is about 820mb, just want to give a heads up, could also use some advice on the best place to upload the file.. Thanks.. P.S. included image shows similar setting to my exported file, difference is triangles 100% and textures 2048..