the second thing is factory over-clocking. Im tempted to pay alittle extra and get the 10% over-clocking.
I'd say - avoid the extra cost of factory overclocking.
Overheating would not be an issue with the sealed unit H2O CPU cooler.
To get the most of of your system you'll want to eventually overclock above 10% anyway. You'll have plenty of time to read up and learn how others have been doing FX-4100 OC'ing.