Hi,
for question #1: were you able to upload a contact with a single quote in the middle of their email address to eloqua? (ie, abc'de@example.com?)
Yes. We have an entry with apostrophe (A'pos's4@techx.com) in our Eloqua contacts. It was inserted as test data for REST API. I tried exactly same entry in filter.
for question#2: thanks for clarification. We'll monitor our live data for quotes and implement change at our end.