It's currently not possible in a single filter to view all users who did not donate in a certain time span. It's necessary to add all donors to a list, filter for donations that happened before/after the date range in question, and removing that filter result from the previously created list. This means that this grouping of users could not be the recipient of an email blast, or have a tag added to them.
Absolutely - We have a list of things that we'd like to fix in our payments and we've added this. We will let you know if there are any updates.