Oh.. It looks like when I refresh my workspace, the Filters go away, so I am assuming they are part of the workspace, and not something that is currently save-able. Is that accurate?
Ans#1 You cannot share the filters only created on one Serverprofile with others. The filters stored in the ServerProfile itself. You can share the entire ServerProfile with another user.
Ans2 Yes you can edit an existing filter without recreating one. In UI open the serverProfile --> snapshot tab --> you can see the list of filters that are currently available in the Serverprofile. Highlight the filter you want to modify and hit "edit". This will open up the same Snapshot Filter Wizard where you can make your changes.
The filters should not go away with a refresh of workspace. You have to save the ServerProfile after you add the filter.
Nodes, filters, tokenstes are local to the ServerProfile.