yes that should be fine, but just google and you will find a lot great ideas for ESX home labs
Two cores is the minimum supported with ESXi. It would work, but - not surprisingly - the more cores you have the better the system will perform.
Even for a home lab system I would start with four cores. The price gap from dual to quad core shouldn't matter.
Just to add to that, the AMD x6 Phenom also works pretty well for running VMs,
It will be fine, especially with just 1-2 VM's. You should see all of the crap I have running on my i5 MacBook Pro.