I'm male and have done the whole gamut of hair regrowth options (graft + Finestride + Minoxidil both topical and pill forms). I'm pushing 40 and my hair is basically back to where it was in my early 20s.
In terms of how well each worked i'd rate them like this:
#1 Graft #2 Finestride #3 Topical Minoxidil #4 Pill Minoxidil
Obviously grafts are expensive but holy-cow do they work! Grafts are your only option to restore hair after a follicle has died (you can tell if an area of the scalp has dead follicles if the skin is smooth and shiny). You can cut the high cost by over 2/3s with some research and a trip to Turkey and I know several people that have done this with great results. There are entire flights of people just getting graft procedures there from the US and Europe. I opted for staying in the US and take the wallet hit for logistic reasons since I have small kids.
Finestride probably won't be an option for you since it attacks DHT which is what causes follicles to go dormant in men. I take 1mg per day and technically this is all I need to take to stop most of my scalp follicles from going dormant. Combining this and Minoxidil is what got me the best results since they work by different mechanisms.
Topical Minoxidil (Rogaine) is likely your best option. It's just a vasodilator so there's little worry about hormonal reactions. My wife has been using it though it's only been a few weeks and it takes months to really see results. It's kind of a pain to use, since you have to apply it twice per day forever basically. This is why I opted for the pill version. (Bonus fact: you can buy topical Minoxidil in bulk at Costco! A six-month supply is $50 at mine)
Pill Minoxidil is a bit of a mixed-bag. As I mentioned before I use it for convenience as I got tired of the topical. It puts significantly more of the substance in your bloodstream so side effects are more likely (though I haven't experienced any) and it's not as targeted to the scalp. It's basically a blood-pressure medication though the levels needed for hair regrowth are lower than for blood pressure. If I wasn't already taking Finestride I would opt for topical Minoxidil instead
It wouldn't hurt anything AFAIK. It's just increasing blood flow to the follicles in your scalp (they go dormant and die due to a lack of blood flow). In fact, it's better to start using it BEFORE you notice hair loss because it can only help still-living follicles. Nothing can bring back dead ones without a graft.