Yes, please be sure to test that wallyworld tent in prolonged rain or under a sprinkler! It's also a good idea to test your rain gear for at least 30 minutes in the shower.

Listing the weight of each item would help. For me, a digital postage scale weighing to the nearest 0.1 oz. is one of my most important gear items. I take it with me when gear shopping. I gather you do have a spreadsheet--in addition to using it to control your pack weight, it's also great to print out as a checklist when preparing for a trip.

Have you checked out the articles on the home page of this site ("TLB Home"), especially the gear lists and the "essentials"? Those should help you a lot!

On the clothing: While I do take layers enough to keep me warm and dry under the worst conditions I might encounter, the only "spare" items I take are socks. You mention T-shirts--please leave anything cotton at home. It gets extra heavy when wet, takes forever to dry and can be a sure ticket to hypothermia. You can find lots of synthetic breathable stuff at wallyworld, K Mart or Target (check the athletic wear sections). Thrift stores are another good source.