Are S7-Xplorer connections for technostrings or outputs counted against the connection limit?

Technostring connections do indeed count separately against the limit.

Outputs, however, are not distinguished from inputs. Any Xplorer module will be visible in the Hardware view as well as the Outputs view and data will be sent over the same connection in both directions. This means that for inputs (Hardware) and outputs you simply have to count the Xplorer modules.

Chuck Norris has counted to infinity. Twice.