Edit: This was my first answer, but it is not correct
afaik, the number of licenses will stay the same on renewal. If you have a Standard membership with 3 licenses and renew, you still have 3 licenses.
If you let it expire and buy a new membership (which will then be without discount) you have 3 additional licenses, but note that you actually aren't allowed to use updates on the 'old' sites licensed.
This is still correct
Upgrades are already discounted to my knowledge, but you won't get additional time I think when upgrading from standard to developer.
However, any binding statements can only be made by email@example.com.