While I can't give you a wife's perspective on this, I can perhaps offer you some thoughts on things.
First, being a firefighter is the best damn job on earth. Simple as that. Your husband will love it, and you'll either learn to love it with him, or learn to tolerate it.
For most departments of any size, he'll have to attend an academy. These can range from 8 to 18 weeks, but usually lean towards the latter. While he's in recruit school, that school will be his life. He'll come home dirty, grouchy, hungry, and tired. Then he'll have homework to do to get ready for the next day. This will tax your marriage, but it will be important for both of you to remember that these few months will lay the foundation for the job he'll have for the next 25 years. Be patient, it gets easier (well, a little bit) once he's got that badge pinned on his chest.
MOST career departments work 24-hour shifts, but not all. However, these are all kinds of variations on days off. 24/72 is popular, as is work/off/work/off/work/off four. Check with the departments he wants to apply for to see how their days-off work.
One thing that will take getting used to is not having someone who can generally just drop everything and run home when the toilet overflows or something of that nature happens (not implying that you would, but some wives expect that). You'll become self-sufficient!
Few FF's make it rich doing this. Make sure that if you're going to be a stay-at-home mom, that you all are financially stable and good at money management. Do you want him to have a second job to make up for decreased income? Or will you live frugally and he can spend a ton of time at home with the kids?
Finally, very few applicants make it in on their first try, especially with their "dream" department. It often takes months, if not years, of tests and interviews to get on the job. But once you're there, it's definitely worth it!
Not sure if this helped or not, but there are plenty of us on there that'll try to help....