No problem. Glad to be able to help. remember some of the stuff will be freebies from the shop. So you may not have to pay for some of these items. Always bargain.
You can do anything you want, question is if the result will be good. Personally, I feel that stacking filters is not a good idea if stacking them do not serve a specific purpose. Even when I do night photography, I take off all my UV/protector filters. This is because, every piece of additional glass in front of your lenses can degrade your image quality. It can also cause ghosting and flare. In certain situations, I stack filters, but this is ONLY when I use the cokin P filter system, and ONLY when the situation demands that I use more than 1 filter to achieve a certain effect. One thing I always tell myself: Less is More. Keep it simple. This is just my personal opinion. Others may have a different approach.
Free filters may or may not be the best. Most of the time, free stuff are less than spectacular. Shops run a business, they want to maximize profit, always remember that. I gave you a link to the good brands in a previous post in this thread. Read it up.
Lenses meant for FF (full frame, like 5D, 1D) can also be used on cropped sensor cameras like the 500D. It is harder the other way round where lenses made for cropped sensors when used on full frame cameras have the tendency to cause serious vignetting.
Is it not that EF-S lens are physically locked out from mounting on EF mount cameras?