To be honest, mounting the motherboard should be higher on your list of concerns. It's absolutely critical you avoid a grounding issue which can either lead to hours of frustration in troubleshooting, or a dead mobo (or both). Be sure you use standoffs between your mobo and case and only on the places where a screw will actually be used.
Paste vs Pad - Do you plan on overclocking or swapping the processor anytime soon? Using the included pad is just fine for regular usage, and I might even recommend it if you're already nervous about this experience. For best thermal performance however, you want to scrape that pad off with a credit card or other such non abrasive material, then proceed to clean the heatsink with q-tips and isopropyl alcohol (greater than 90% highly preferred). Alternate wet and dry q-tips until no more gunk shows up, then give it a final buff. On a new heatsink with an unused pad, this is a very short process.
CPU Installation - This part is a snap. Look at the arrow in the corner of your CPU and line it up appropriately. It will only fit one way into the socket and will 'slide' right down if you've lined it up correctly. Lock it in place and you're all set.
Heatsink Installation - This can be a daunting experience for any new builder, as some of them require a quite a bit of force. Some are easier to install than others. The best tip I can give is patience. Some require using a screwdriver or other such object to get it clipped on, and you want to be careful not to let it slip and scratch your mobo. The good news is once you've done this a couple of times, you'll see there's nothing to it. Line it up, apply the force, and clip it on.
Antistatic Bracelet - Attach to any metal part of the chassis.
EDIT: Found a short tutorial with pics for ya - LINK