OK, I've figured out I can turn on Pro sharing by opening the database back in FileMaker (not server) and setting Sharing in there, then reopening in Server. Still be good to know if I can do this from server (if not sounds like a feature request), and how to turn on XLST/XML/PHP.
For a database to be shared on FileMaker Server with whatever protocol, there must be at least one privilege set with the Extended Privilege to use each protocol.
In you database (while it is hosted), go into File > Manage > Accounts & Privileges. Go to the Extended Privileges section and turn on each privilege for the appropriate account(s) - [fmapp]*, fmxml, fmxslt, fmphp. That should do it but just in case, go into the server admin and close the file and then re-open it. All the ticks should come up.
*[fmapp] is the extended privilege for connecting using a FileMaker Pro client
See how that goes.
Got it, thanks David.