SD plus Time Machine - Restoring?

[rh26]

So here's my proposed backup strategy. I welcome all critiques. Questions follow at end.

I have an iMac with 500 GB HD.
I have purchased a 500 GB FW drive for SD backups.
I have purchased a 750 GB FW drive for Time Machine.

Plan is to connect the 750GB drive and allow TM to run continuously.

The 500GB SD drive will be used to clone the iMac, and then the drive stored off-site (at work). I will bring it home once a week or so to do a Smart Update and return it to work the next morning. (Obvious downside to this plan is that the SD backup is 20 minutes away if I ever needed it urgently. And a second drive that I could rotate is not in the budget right now.)

So with this plan I do have a bootable backup if I ever crash a disk. (Plus I can do a backup if I need to take the iMac in for repair, etc.) And I have hourly backups against "stupidity" data losses of single files, directories, etc.

Question #1: Does this approach seem robust?

Question #2: Suppose I have a disk failure in the iMac (the SD clone could be up to 1 week out of date). There are two recovery scenarios, but I think they are effectively the same.

Scenario 1: Run to the store and by a new drive, swing by work and grab the SD clone. Install the new disk. Clone (restore) the SD backup to the new internal iMac drive. Now mount the Time Machine disk. So how do I restore those files automatically? Assume I don't even remember the exact date I last ran SD on the clone. How do I tell Time Machine to restore everything that's not already there or out of date?

Scenario 2: Assume I have to mail order a drive and get someone to install it and so I need to restore the recent TM changes to the SD clone drive and run from the clone for a couple days. (I know at this point I'm living dangerously.) I assume the TM restore procedure would be the same as Scenario 1...

Maybe I'm missing something but I can see how to do a TM restore to a virgin disk. And I understand how to do single file restores. I'd like to rest easy knowing that using SD plus TM allows me to do a simple 2 step restore...

Thanks,
Robert