I just got done doing this a couple of weeks ago.
Drivers can only be installed on the boot drive, so you don't have any choice in the matter.
The Win7 install will take up roughly 20GB or so on the SSD. You will have plenty of room for a couple of your most-used applications/games. Just make sure you have at least 10GB or so free space at all times.
The OS install is simple -- just have only the SSD and optical drive plugged in when you do it. After the OS is completely installed, do a shutdown and connect the platter drive.
To have all of your data and documents on the platter drive:
Open up your C: drive, and navigate to the Users\YourUserName folder. Copy down all of the folder names.
Open up your platter drive (E: on my system) and create a Users folder. Then create a YourUserName folder within that. Then create all of the folders you copied down within the YourUserName folder. Close out of everything.
Open up your C: drive again and navigate back to Users\YourUserName. Right-click on the first folder in there and choose Properties. Click the Location tab and click Move. Browse to the first folder you created on the platter drive (likely E:\Users\YourUserName\Contacts) and click Select Folder. Answer Yes.
Do that for all of the folders (C:\Users\YourUserName\My Documents to E:\Users\YourUserName\My Documents, etc.). Now all of your documents and downloads will automatically save to the platter drive.
I found the above method better than the other registry-editing method (I always got error messages after doing the registry method).
You will have to manually select the platter drive as the install directory (I use E:\Programs\ProgramName) for each program you install when you install it.
For other stuff you should do:
SSD Optimization Guide