Question : What hardware is best suited for "number crunching" web applications?

I'm looking for advice to specify the purchase of machine(s?) which will host "number crunching" web applications. It is critical not to have downtime. It will not be dealing with network routing issues, but there may be many simultaneous executions - that makes multi-cores and disk access considerations very relevant I guess.

Answer : What hardware is best suited for "number crunching" web applications?

doesnt' really mater, in both cases you can use only certificate per service

get a public certificate with the fqdn you need  i.e.

mail.domain.com (assuming this is your owa url)
autodiscover.domain.com
servername.domain.int (if applicable)

and then assign it to the IIS service