Hi Christina,
You asked if hair grows back anyway
Well, sort of.

New hair grows in. Since hair grows in stages (I didn't understand how much this was the case until I started laser hair removal) it seems like hair is growing after being lasered, but it's not. So yes, more hair grows, but it's not the hair that was lasered.
You asked about the cost
I've been told that electrolysis costs thousands. LHR cost me just a little over 1 thousand. I suggest you pay upfront if you can. The amount you pay per session could end up costing you hundreds over one thousand. I've heard someone who paid at least 10 thousand for electrolysis.
You said think of it as an investment
I TOTALLY agree with you there.

If you think about the money you will spend on razors and products over your lifetime, it's worth it. Then if you add the fact that you're a CD'r then it's more than worth it.
You asked how long do the treatments last
Bring coffee and an audio book it takes a very long time for each session. Oh wait... that's electrolysis.

It only takes about 20 minutes. My first session could have been a few minutes longer, but I don't think it's been over 30 minutes.
You asked is it painful
Yes and no. The stinging after the treatment lasts for about an hour after the session. During the treatments it feels like rubber band snaps that are pin prick size. If you're wearing the topical cream you can still feel a sting, but it's not even close to feeling like it does without it.
The most sensitive areas are above and below the lip.
I said "No" about pain because it's very temporary, unlike I've read about electrolysis. The burning is similar to when you shave really close and then apply after-shave. Honestly, that's what it feels like. It feels like the aftershave takes about 45 minutes to dry.
Only once did I have some swelling and it lasted until the next morning. The area was 2/3 the size of a dime. I haven't ever gone to sleep after a treatment and still felt the tingling or burning.
You asked can it be done in other places
When I'm in the waiting room, the women coming out have usually come from having their legs done. I was told of one woman who had her legs done before she went to Africa because she knew there would be no way to shave there. She reported she hasn't shaved in over a year.
Now for stuff you didn't ask 
I consistently hear that electrolysis takes
years. Laser is simpler, less expensive and more convenient and takes a fraction of the time.
I would also like to tell you all I haven't shaved in over a week and it looks like I shaved this afternoon. I have had a total of five treatments. I doubt that I'll have more than 7.
Thanks for asking these questions Christina.
I beg of anyone to ask questions. It can only help those who are considering this for themselves.
Beauty