Random bitflips in radiation. OH HELLS YES!
Basically to avoid unexpected program behavior or outright crashing in radiation will then require a vastly different programming paradigm. One which is fail-safed all to hell (checksums, redundant code, ect) and perhaps even whose opcodes are specifically chosen to avoid instructions mutating into something particularly hazardous.
On the topic of generators, I don't really see it being a problem. In order to actually make use of any substantial number of generators, one would either already be spending all day in the game or need a bunch of buddies freeloading off them. Selling power probably won't be too problematic either, as any sort of 'batteries' will almost certainly be very limited; anything more than a full generator of output would probably be much more hassle to sell than it was worth, simply because batteries are physical objects, and as such I wouldn't expect players out in deep space to be able to sell them without returning to a station (though I may be wrong). Generators will probably be very cheap, as the fee is to pay for the server-side computation of the things they run; which isn't a very big cost. My bet would be everyone has as much power as they need simply because it will probably be a low enough RL cost.
Computers will have wireless communications, but it takes much more than that to hack into a computer. It needs to be running a program with some sort of bug or exploit that reads from that communication, the hacker then needs to send the correct message for that particular piece of software to respond in a way they want. Both aren't all that likely, since DCPU programs are much more low level and simple than modern programs, meaning less vulnerabilities. Secondly, people's choice in programs in a game where programming is a bit part of gameplay will be incredibly diverse, with a large chunk being written by the person who is actually in the ship. Thus tailoring an attack to any given ship will be really really hard unless you know in advance the weaknesses of that particular guy's system.