Extents per table:
select * from sysextents
per extent the offset in the dbspace and the size in pages. Do a SUM(size).
select * from sysptnhdr.
In the system catalof in systables you can also find some info on extents.
Locks and buffers per table:
select * from sysptprof
total amount of lock requests and lockwaits per table since server came up. bufreads and bufwrites per table.
Do you want to configure two servers on one machine?
Do you currently have performance problems?