This is pretty confusing but one thing is certain, data recovery on harddisks that were in a hardware based raid are extremely difficult to recover any data from. Almost impossible in fact, unless you use the same model raid card that created the array afaik (since each raid controller often has its own method of writing data to a disk).
Ensure any thing you do these drives is read only. changing even a few bits will likely fuck the entire array.
If you had 3 disks in the raid 5 array, and only 1 was damaged, you'd be ok restoring the data with the same model array controller. If you only had 2 disks in the raid 5 array, and one was damaged, you're screwed.
As mentioned in the previous thread, you're best bet (based on your scenario) is going to a hosted solution, you could be up and running in 1-3 days. Trying to get a new Exchange server online is going to take several days of configuration and testing just to get something working, which likely wont be exactly what you want and you'll have to start over. Exchange 2010 is a very complex server (to get configured properly), even for those with some exchange experience.
At the least you could go to hosted exchange for a few months while you play with, learn, and configure your exchange server in the background. With Microsoft Office 365, you can actually run both their cloud hosting, and an on-site exchange server, having some accounts locally, and some in the cloud.
You can also use a service like mailroute, which, in a case like this, would actually hold your email until you have a server back online, at which point it would release all your messages to the server.
If just the harddrives are having difficulty, you might be able to restore their functionality with spinrite. The program works on individual drive sectors and doesnt give a shit about the type of the actual data (ie file systems, formats, raids).