As for the recording software, I highly recommend Audacity
. Having done audio and video recording and editing for a number of years (well, at least until my hearing went too far south to do it anymore) I've worked with a wide range of programs, and Audacity is unbelievable. If you've ever worked with Sound Forge, you'll know that it's the number one audio editor in the <$3k price point.
Audacity is easily equal in quality and power to Sound Forge, and the best part is, It's FREE
!!! I used it when I did my first recording of my audiobooks (I have since had them professionally recorded) and it worked beautifully.
As for work times, I've found that for every 20 minutes of play time you will end up with about an hour of work. If you're really, really nitpicky, two hours. Another thing to do when you're first starting out is to create a test recording. Practice your reading style, character voices, inflection, etc. Don't be afraid to make mistakes. The best part about screwing up is you can learn from it and get better. Also, be patient. This isn't a point, click and you're done operation.
Most of the time I spent the better part of a week working on a six hour audiobook getting it ready, tweaking and polishing. Also, invest in a good pair of noise canceling headphones for doing your editing. The reason being, as you go through the recording, you'll need to be able to hear all the clicks, pops, and other awkward noises so that you can spot them in the recording and apply filters to clean them up.
Also, pay close attention to your levels. If there's one thing people hate, it's an audiobook with volume issues. To provide an example of what I'm talking about, think about what it would be like if you were listening to a song on the radio and kept having to raise and lower the volume constantly because the volume levels changed. You don't have to be perfect with your levels, but at least get them as close as you can to even. If you need to, get a second opinion on how they are, and then tweak away.
Anyhow, I hope that helps you out a bit. And please, don't be discouraged by any advice given here. Recording your own audiobooks is fun, exciting, a great exercise in writing perfection (It'll actually help you see problems in your writing, and learn how to fix them), and a good way to promote yourself. Especially if you offer them for free!
Anyhow, good luck.