No, I never counted in the rebates, and here are some more answers to your questions...
1. Yes, the motherboard I suggest is good for overclocking, I chose that motherboard for you because the UEFI Bios is meant for first timers, and is EXTREMELY easy to use.
2. ATX is a motherboard size, the standard case can hold an ATX size motherboard.
3. PCI-e slots are for video cards.
4. AM3 is the CPU socket, modern day AMD processors are AM3 socket, and soon they will come out with an AM3+ socket.
That is the BIOS on the motherboard I suggested you.