I've made an android app before to link with nxt via bluetooth, sending the gyroscopic measurements to the nxt using APP INVENTOR and robotc

I am wondering whether this is achievable not through app inventor, but through eclipse using the ADK plugin . I know this can be done using leJOS but am an unsure with RobotC because I can't seem to find any online.

Yeah, it is pretty easy. I used intellij at the time because it was less buggy. They probably have worked out the problems with eclipse by now. but the adk is the same.

http://www.spiked3.com/?p=253

Actually, thinking about it, I didn't do anything on the NXT side - I use LCP, aka direct commands. If you need to actually have code run on the NXT side you can use bluetooth serial, or XBees (see other articles on my site).

I do not know of a way to read serial from the USB connection though. You can read sensors, run motors, even read encoders without any code on the NXT side, although it is slower than if you had code running on the NXT.

Honestly, I have little clue on how to program for android. What would you suggest?
I've only every programmed c++. And that I started half a year ago.

Java is fine. If you've done C++ you have enough to dive into java. The documentation can be a little frustrating, the technology seems to always be moving ahead of tutorials you find on the internet, but know that up front. So look for a simple 'getting started with android' kind of thing. Then form some idea of what you want to do with the NXT. Next, there are a few open source Android/NXT projects, including the one from LEGO (minddroid or something like that?). I used it and got all I needed to do my project at that point.

Good luck, feel free to ask questions, although robotc might not be the place, email if you want spiked3#gmail#com.