Another hiker here! Hiking is fantastic exercise, especially if you work up to difficult hikes that include climbing to work your upper body at the same time. General hiking though is awesome for your butt and the muscles in the upper half of your legs (front and back) because of uneven terrain and hills, it's kind of in between cardio and lifting weights, you're working your muscles a little more strenuously than if you were jogging or walking, but you're still working up a sweat and raising your heart rate so you get those cardio benefits.
I'm in Arizona and I do a lot of hiking in the phoenix mountains preserve. One thing that they tell us here (because of extreme heat) is to eat salty foods and drink lots of water, the salty foods make you retain water so there's less chance of becoming dehydrated, I usually choose beef jerky and mixed nuts.
Do a general internet search for local hiking guides (if there's anyone in my area I'd suggest
www.hikeaz.com and start out on heavily used trails, they will be marked better than the obscure ones.
As far as equipment goes I use trail running shoes because I go between traditional hiking and trail running so I need a hiking shoe and running shoe in one.
HERE is a good article that introduces you to some of the best/favorite trail shoes. I personally use a pair of Adidas Supernova Trail Runners (so comfortable and supportive). But you don't need special shoes to start out, your sneakers should be just fine in the beginning. When I'm going on an extensive hike I bring a very small backpack for water, snacks, first aid, etc. When I go trail running it's usually for not more than an hour so I don't bring supplies, they usually just hinder me.
Just get out there and have fun in nature, hiking is one of the best forms of exercise out there in my opinion!