Finding a literary agent

My husband wrote a book. He's still writing the second in his series now. He's had this all in his head forever, but finally found the time to get it all out in the open for the rest of us to enjoy. I'm acting as his proofreader/editor, and have been slogging through this for weeks. It's really a good book, although it's a science fiction work, and that's not generally my favourite genre to read. The biggest issues I've found so far have been punctuation errors (he just wrote and really didn't care about correctly punctuating) and some passages that are worded funny (because he's not a native English speaker, sometimes he doesn't know that x would sound better than y).

He also assigned to me the task of researching literary agents and sending queries. I'm lost. I've had an agent in the past, since I used to do voice-over work, but that's a far cry from what he's asking me to do. So I've been perusing the web, trying to find as much information as possible on who represents sci-fi authors, who's reputable and who's not, and then once I have found the right person/people, what to send to them and whether they accept queries by email, fax or snail mail.

I'm preparing for rejection letters, but maybe we'll find someone who loves it and he gets published. I'm hoping for the best, but ready for the worst.