I'd be suprised if Solaris 10 for Intel (x86) was troubled by multiple cores or CPU's but then I am not a Solaris for Intel expert.

Can't comment on VMWare apart from I have used Solaris 10 for Intel running in VMware on an ESX server but that would not surprise you.

As far as running Linux applications on Solaris for Intel it can be done, take a look at:
Sun's Linux Offerings - Compatibility: lxrun
and:
http://www.hackitlinux.com/50226711/running_linux_on_solaris.php

HTH