Windows 7 install - space & license version request

Hi all. I'm thinking about putting windows on the MBA, and have a couple of questions.

My needs are very limited for Windows, notably MS Office, Access, MS Project type stuff plus Quicken since there's no good Mac alternative to Quicken.

I have a 256 SSD, and the MBA is my second machine for travel (and for windows use), so I doubt I will ever fill it up.

I do not think I will need to run Parallels.

Questions:

What W7 license should I get and why? (version, OEM vs. not, etc)

How much space to allocate for the windows install?

Finally - is there a good tutorial about doing the install that someone can point me to?

Thanks!