Not sure what is available in your area, but have you considered renting to start? If it is an option in your area it would allow you to try out some different shelters, sleep systems and other gear to see what works for you. If not I'd avoid shelling out a lot of money on high end equipment until you are sure you are in it for the long haul. Stick to reasonably priced stuff that has good reviews and you can always upgrade items later which is part of the fun.

On the boots I'd recommend looking for stores in your area that carry the major brands and trying them on. You can buy a lot of stuff online, but not boots. I am breaking in a new pair of Keens right now that seem to have a nice wide toe box but I'd never have guessed I'd need a size 14 if I hadn't tried them on in the store with my good socks on.

For shelter it depends a lot on where you'll be going. Up here the bugs are terrible so I prefer a tent over a tarp and freestanding is important because I go a lot of places with lean-tos or platforms. I have an old NF Tephra 22 but I think they stopped making those years ago heh.

I'd advise looking into a down quilt rather than a sleeping bag for the seasons/area you mentioned. I picked up a 40 degree Thermarest Ventra over the Winter I'm looking forward to trying out if it ever gets that warm again and am really happy with the size/weight savings over my old bag.

Backpacks are another item you really need to try on to see which works for you. I am an Osprey fan myself but what fits you is the one you want so try on as many as you can preferably at a store with knowledgeable help. Wait until you have most of your other gear before you look for a bag though. You won't know what you'll need to carry your stuff until you have your stuff.

You'll definitely want to do a lot of looking around the site here. There are a lot of people here with a lot of experience with what is out there and many of them have shared their thoughts already. Sometimes they even agree Good luck and have fun out there!

Edit: Speaking of knowledgeable people with a lot of experience I see a few of them posted while I was typing