Re-posting my email response to you here.
All of the fonts in Typekit are available for commercial use. This covers almost everything you've listed in question 1, as long as you are only using static graphic images in-game (eg. PNG). It is not possible to use Typekit fonts in an HTML email reliably, so we do not support it at this time.
3. Are the fonts OK for worldwide usage, meaning the assets we create may be distributed worldwide?
>> The assets created may be distributed world wide, as long as you are not attempting to distribute the font software or embed the fonts in a document that allows third parties to create content.
4. Can the fonts be modified? (ie, let's say the letter "W" is hard to read. Can we modify it?)
>> You can modify a vector image of the fonts, but not the font software itself.
6. Is distribution of an asset OK perpetually after that asset has been created? In other words, if we make an newsletter using Creative Cloud and then later discontinue our service, that newsletter can still be distributed, correct? So long as the asset is created while our subscription is active?
>> Yes, you can still distribute documents you created with a subscription after the service is cancelled. You will not, however, be able to make changes and opening editable files will result in a missing fonts warning.
Thank you for the reply. I will mark this as answered.