Not bad at all for a first crack.
First of all unlike photography, astrophotography processing is a little bit different as the colour reproduction generally is spread over so little of the histogram its not that the data isn't there.
As for your image the tracking looks alright, but the colours are a long way off, the black point is clipped. Use something like Photoshop to inspect the raw image (not processed). Use Levels to bring the histogram into line The RGB channels should line up pretty much and that will give you basic colour balance.
With your black point and white points don't go too over the top. stay clear of the tail of the histogram as thats where your faint data sits, cut this the background goes nice and black which is bad
Ive found Deep sky stacker a great tool for handling large raw bayer DSLR images its computer friendly on resources. Nebulosity is a decent capture tool, but so is Backyard EOS, and a number of other ones as for cross platform. Well i got cluey

I run with a little eeepc and there for you have no issues with getting programs to sing together Mac although it works on some it can be a nightmare on others... whats a few hundred for a dedicated Telescope/Camera/mount controller that you can log into via something like Team viewer? very handy.