Custom WIM image to be deployed through SCCM 2007 r2

The XP install disk puts the needed magic spice in the MBR on the disk. Until this is done the windows bootloader never runs.

The SCCM client polling interval is a configurable setting that applies to all clients in the site. Sounds like it's set to 30 minutes at your site but (depending on network limitations/server load) this can be safely changed down to 15 minutes by someone with the appropriate SCCM site access.

There are ways to force a machine to check outside of its normal polling schedule.

There's an open source tool called SCCM Client Center that you can use to connect to a client machine and check/set a lot of the SCCM details with (as long as you have the appropriate permissions).

What you can do is once you've placed a machine in a collection, rather than waiting for it to poll you can connect to it using the Client Centre, select Client Actions -> Download Machine Policy, then wait a minute or two and select Client Actions -> Apply Machine Policy. This forces it to connect to the SCCM server collect any pending policy changes (eg new adverts) and then once they're downloaded you tell it to run them.

Setting a timer on the job running is down to whoever set up the advert for the job in the first place, they had a number of options they can pick for scheduling the job once it's picked up by a machine and presumably in this case picked "As soon as possible". You can also set up Maintenance Windows on machines that set when jobs can/can't be run on them which would stop builds happening in working hours if that's what you want, but it sounds like these parts are outside of your control unfortunately?

I could be mistaking how you're set up but normally once a machine's set up in SCCM you don't need to know it's MAC, and if you ever do you can just find the machine in the console right click it and look at it's details. Adding machines to a collection can be done by machine name, MAC, IP or pretty much any criteria, you only need to know one unique thing about it.

New 'bare metal' builds are obviously slightly different but we don't currently use that part of SCCM (but are planning to move over to it) so I can't tell you much there.