Hi @Albany. I apologize for the delay in my reply.
#1 - For Contact Activity in segments, there is a limit of 25 emails that will show in the dropdown when selecting a specific email. I've noted your feedback and sent it to our product team as I can see this being an issue if users send frequently.
#2 - I brought up your account and saw 50 custom fields displaying, not the 20 or 40 you mentioned which might be a browser issue such as screen size or zoom setting. Additionally, the custom field dropdown in segments is limited to 50 custom fields. Since you have more than 50, not all of them will display and the segmenting will need to be manually done outside of Constant Contact as you noted in #3. Expanding the limit of custom fields is a request that we have heard as well.
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