heh, lets see
-Not sure on the "best" AMD mobo at this time, I'm a big fan of EPoX, or Asus.
-I get nervous around chip CPUs ( I Miss the slot 1 cpus

). They're fine enough if you are cautious with 'em, but the pins can bend quite easily.
-AFAIK there should only be a "missing" pin on 1 corner. This helps in CPU orientation when putting it in the socket.
-Gel stuff = thermal compound, allows for better heat transfer to the heatsink. Pretty much necessary. Arctic Silver is probably the best you can get, pretty much everyone sells it (just get the thermal compund not the epoxy

). Some retail heatsinks come with thermal pads in place of compound, this would be ok if you weren't OCing. But most folks wipe the pad off and use compound.
-Typically heatsinks have spring-loaded arms that attach onto lugs surrounding the socket. If you aren't careful you can possibly break one off (made of plastic). Some high end heatsinks screw into the motherboard.
HTH.