Sizing is not too difficult if you consult the charts and search for reviews. Most reviews comment on size or your can private mail the poster. Most brands follow European sizing so they run small. If you get a little experience with the brands, you will know how to order. Some brands I require a large and others I take xlarge. Shoes are the exception. I recommend trying them on and purchasing locally. I tried on several brands and models and found one that fit like a glove and I liked much better than any of the others. I have been extremely happy with my purchase. Shoes and pedals are critical purchases and IMHO you need to try them.

Regarding tires, if you are that discerning you will just have to try some until you find the ones that you want. If someone recommends a high quality product and you do not like it, then you are on your own. Anybody's guess is as good as anybody else's, so it might as well be yours. I personally can't tell one tire from another. My criteria is that they don't lose grip or flat and last a reasonable number of miles. Other than that they are pretty much the same.

Regarding the clothing ordering, his terms are the same as everybody else's.

It helps if you have realistic expectations.