>>>is there a limitation as to how many partitions can be created?

Docs say the limit is eight.  Of course there is overhead associated with scheduling a partition so you don't want to 
create more than necessary.

>>>>>>do the user apps have to bundled together to form the "user partition"?
Not sure what you mean by "bundle" ... but there is no change to the binaries.  You either start the binary in the 
correct partition or "move" the instance to the correct partition after it starts.

Use "aps" command to create the partitions.
Use "on" command (-X) to start an instance in a particular partition.

Dennis