Magento expert needed

I have a few issues in Magento that I need immediate help with: 1. Checkout page where customers enter their address and click continue to proceed - "Continue" button does not work for one page credit card checkout. Checkout via Paypal works fine. 2. Cannot save changes to or new products. It just comes up with the loading circle and hangs. 3. Cannot expand category tree in "Manage Categories" section. When you click on the + sign, it just disappears and the folders don't expand.