License Transfer w/out Old 360

So I'm thinking about selling my 360 since I just bought a gaming PC.

My question is what will happen to my purchased XBLA content. If I wipe my HDD, sell my current console, and then buy a replacement console at some point in the future, would I be able to redownload my previously purchased content? Or do I need the physical HDD from my prior console? And if I copy my game saves to a flash drive, will those transfer no problem?

I've only ever had to do a repair for my RROD console, so I don't know how easy/complex the license transfer is. I'm hoping it's as easy as it should be. Is it? Does it simply follow my username rather than my console?

And is there anything else I should be aware of when preparing my console for sale?

Cool. Thanks.

Now if I only knew what the situation will be for 720 backwards compatibility... I'd probably just wait it out until then. Plus I have a few region-free Japan-only titles that I'd like to hold onto (and hope to play again some day). Fingers crossed.