Here are a few nuggets that I've found helpful to note. Mainly I'm putting them here on my blog so I can refer back to them in the future ... if others benefit that's a BONUS! ;-)
The limitations of the TechSoup Microsoft Software Program can be summarized down to the following:Within a 2yr window which starts with your 1st purchase...
You can purchase up to 50 licenses per Title Group across 10 Title Groups max...this includes server cals.
You can purchase 5 server software licenses
No, you can not renew Software Assurance via TechSoup. You must use an authorized charity reseller for renewals. However, in most cases it'll be cheaper just to purchase again from TechSoup unless you're over the above quanity limits.
After your 2yr window, your licensing allotment resets to zero.
If you want the read the full monte, TechSoup has a great page explaining the above in detail along with handy purchasing examples http://www.techsoup.org/support/articles-and-how-tos/microsoft-eligibility#allotments
TechSoup Microsoft software includes Software Assurance ... which is awesome!
Basically, that'll give you upgrade rights for 2 years, usually home use rights for employees, and online training resources.
I'll update this with other helpful nuggets I or other church IT peers uncover...so if you have nugget to share leave a comment below :-)