6.4.2 When did you first meet your sponsor? The answer to this one is when you first met in person.
6.4.3 Where did you first meet? The answer to this one is "Online" if that is where you did first meet.
6.4.4 When did your relationship begin. Again the answer is when you first met online.
6.4.5 How often do you meet? I don't know the answer to this one as it didn't appear on the visa form when my wife applied. The best thing to do is to email them at ManilaVisaEnquiries.manila@fco.gov.uk and ask them what sort of answer they would expect in the current circumstances of both your wife and yourself. I expect that something like "Very Infrequently" or "Very Infrequently at Present" would suffice, so you could also ask them if either of these answers would be acceptable.
The first three answers I gave you are correct, because this is what they told me when I emailed them for clarification of these questions back in 2006.
Iain.