Fate of current backups when changing disk

Question

I'm having trouble finding info here or in desktop help to support a strategic decision about how to deal with a Time Machine backup partition that's getting full. (After I broke down and bought iWork and iLife, four years later, and installed them the other night, TM announced its disk was full and my oldest backup was now from Dec. 1. Its files had previously gone back to August.)
I have another partition with about 30 GB more available space than my backups currently occupy. Maybe 40 GB more, with some housecleaning. My impression from what I have been able to find so far is that under Leopard (NOT Snow Leopard, can't run it) I have four choices:
1. Duplicate current TM partition onto new TM partition. This will transfer existing backups to the newly designated partition and allow TM to pick up where it left off, but it will also erase everything currently on that partition, including the OS. Right?
2. Simply switch backup to the other partition. This will cause TM to make a full backup on that partition and go from there. That means I have to keep the old backups on the original partition for a while so I can access them if needed via the "Browse other Time Machine disks" menu command. Right?
3. Enter Time Machine and delete some of the backups, or remove specific items from them, so TM will have more room and won't have to delete again for a while (hopefully, giving me enough time to implement additional storage).
4. Cross my fingers.
Any confirmations, corrections or recommendations appreciated.

Answer 1

This is weird...
I finally realized this morning that for the time being I had enough space on one of my external drive's other partitions that, rather than having to find somewhere else to stash the data on it, I could just subdivide it and create a partition for Time Machine that would be considerably larger than the existing backup partition. I went through the process of using Disk Utility to "restore" the original partition to the newly created one. (3-1/2 hours, ugh.) Then I changed the name of the old backup "drive" in the Finder so it wouldn't be the same as the new one. (Besides encouragement from Király's reply above, my strategy and procedure were all based on the info in the very nice FAQ here--thanks to Pondini for that. Apple's canned support material was almost no help at all on this.)
Everything looked fine to me; the new partition showed the exact same contents as the original backup partition--the backups.backupdb folder, with the same modified date. So I unmounted the G-drive, turned its power off, and went about some other digital housekeeping. When that was done (several reboots and a permissions repair later) and all was running well I turned the G-drive back on so I could select the new partition for Time Machine to use.
Well, the darn thing immediately started chattering away, with its little white light on the front grille flickering busily, although it had not been addressed. Not by me anyway. It continued to be quite active for about 10 minutes, then quieted down somewhat, but it's still making its scritchy-scratchy noises.
What the heck could it be doing?? Is there a way to find out? I'm a little reluctant to initiate the TM disk switch as long as it continues talking to itself. Even if it's something perfectly normal following a partition change, I'd appreciate understanding the behavior. Thanks.