To backup Exchange, just select the Microsoft Information Store under the server.
You would probably not succeed in using BE to restore a new server onto new hardware because of driver incompatibility, etc.
If you need to take full server backup of exchange then you can backup C , System state & shadow copy components & Information store for exchange.
Regarding restoring capability to different h/w you cannot restore to dissimilar h/w with backupexec as it is mean to protect the server you do backup of to restore to dissimilar h/w you can think of using option of BESR. BESR would do block level backup that will backup the entire image of your server & will have capability of restoring it to different h/w
...it's quite possible to restore Exchange to different hardware as it basically doesn't care what it's on. There you're wrong, but right on restoring a full server...which the OP wasn't asking about.