Are you leaving in 16 days and only now buying gear? If that's the case I hope your deliveries will be on time!
Both the backpacs look
good, but I'm a firm believer that when buying a pack you should try it on
. I was going to buy one over the net too, but luckily I opted to go and check it out at a local retailer before purchasing... Let's just say that I'm glad I didn't buy it (otherwise the straps would cut into my shoulders). I ended up buying a different pack, but it felt like it was custom designed for my back.
Looking at the tents I like the Aztec better - if you're using it for backpacking you want to have as little to carry as possible.
As for sandals - I love my Teva's, so I guess I'm biased, but they are great!
A few years ago I bought one of those super absorbant, pack light towels for camping, but I rarely use it anymore. It's good for my hair, but attempting to dry yourself with it in a tiny steamed-up bathroom is a pain... It feels like you can never get 100% dry and I hate that. I'm opting for a washed down (ie: less fluffy, so it will pack better and dry quickly) towel from home.
Sleeping bag - like I said, I'm big into camping, so I have a wicked sleeping bag. My motto is - research it well, buy once and invest a lot - it's money in the bank. Plus this way you won't worry about it in the future. To me buying a 'cheap' sleeping bag means that you'll either be cold or you'll be replacing it within a year. Either way that's a waste of time and money. Buy a good one that is rated for a slightly lower temp then you think you'll need - you can always unzip a bit when it's warm, but it will come in handy for those chilly nights that seem to sneak up on you in the middle of a hot summer.
Hope that helps and best of luck!