Getting a new SSD to replace HDD. Need to know about transfering Windows.

Hey people,

I'll make this quick. I'm redoing my whole computer: mobo, CPU, GPU, the works. Everything except the case and PSU will be changed. I want to keep my HDD for storage and use the new SDD as the boot drive and maybe to hold a few often-used games or programs. All I would like to know is:
1. Can I install Windows on the SDD using the same copy of Windows 7 (64-bit Home Premium) that I used on my HDD? I should be able to right? It's not OEM (and thus tied to mobo) and it's completely legit. I just don't want to run into any crap about license keys or what-have-you...
2. Now, when the OS is on the SDD, what do I do with the old HDD? There is still a copy of Windows on there right? If I reformat it will it eliminate Windows itself on the HDD (Isn't Windows needed to reformat lol)?
3. I've heard that clean installing everything is best (and what I had in mind) so I don't want to know anything about images or drive-cloning or whatever

Any light that could be shed on these questions will be greatly appreciated.

Thanks in advance