Some issues after using 2.1.1 for a bit

Hello everyone. I have had a chance to use CS-Cart 2.1.1, and I have some questions that keep me from wanting to spend that amount of money on something that isn’t working as good as some of the free carts that I have used in the past. Any help would be great. Anyone that just wants to be mean, or tell me to search a million posts on the forum need not reply to this. I can get that disrespectful crap from other message boards, and it doesn’t cost me anything.

– Is there some kind of word-for-word guide to this version of the cart? There are many settings that I have no clue as to what they control.

– My site stopped sending confirmation emails to customers for some reason. Any ideas on how to fix that?

– Orders are being cut off at 100 items when sent to Paypal, which causes them to not pay the actual amount owed. Some customers do order 200 different items from me. Any ideas for why this happens, and how to fix it?

– What is the largest image size that should be uploaded to the site so it doesn’t affect the site speed in the long run?

– I am aware of the fact that if customers don’t click on a link in the Paypal screen to return to my site that the order remains listed as “open”, and worse, the products can be bought by other customers until I manually change it to “processed”. Any way to change that?