1) I'm updating entities from inside the onDraw() method. Is there a better way to update logic?
see answer 2
2) Why does the engine cap at 55 FPS on my 1 ghz samsung and 60 FPS on my 800 mhz LG Optimus E400? It would still report 55 FPS if even if I only draw 1 entity.
Because of frame limit to 60 fps (this is good thing) You don't want to take full system resources and draw everything as fast as it can. However you could update Your logic faster if you want. However 60 fps limit is really good for newcomers.
3) What is a good way to support multiple screen sizes?http://blog.gemserk.com/
everything you need about screen sizes
4) Is there a good Android specific forum I could ask questions aside from here?
5) Can you guys test the apk included in the DL and report your phone model as well as the FPS?
sorry, my android device is dead at the moment