For Boots, go to your local board shop and try on several different manufacturers to get an idea of what size would fit you. Don't listen to the sales guy if he tries to tell you which boot you should buy, figure out what is comfortable and compare, compare, compare. Size is important. Your big toe should touch the end of the boot when you stand up, but when you get a good knee bend it should come off the front. If it doesn't, it's too small a boot. Boots you should not, if you can, go cheap on. They will make a huge difference in your experience on the hill. I also would not buy used boots.
What length and kind of board depends on the style of riding. Some boards are meant for the park, some are for cruising, and some try to be multi-purpose All-Mountain boards. With your weight you're probably around the 158cm mark, for length.
I suggest Craigslist for used board/bindings or anything local. Make sure you can inspect the setup before you buy for anything outside of normal wear (ie. deep gouges, rusted edges, mistreatment) etc. I would not recommend buying used off eBay unless there are a ton of high quality photos you can see.
What is your budget?