Depends on sellers. Some sellers don't respond. PM me items you bought, I'll take a look and tell you if that seller will contact you or not.
Usually, I ask them if they ship and when to expect it.
Nah, you won't have problems. PayPal will refund your money if you have a problem. But not always, so it's good idea to use Credit Card with paypal. Prefferably AMEX. PayPal don't help, AMEX will, they don't screw around like PayPal.