Hi Dave,
The etiquette is the same as asking a friend to do you a favour. Send a message saying "Hi", tell them your problem and ask if they would mind looking for the information you require. When they reply send a message thanking them for sending the information. Everyone on Rootschat is a friend or a potential friend. That's what makes this site so popular. I think a couple of Rooney queries have already been posted. If I'm correct there's one from a member wanting information on Annie Rooney from Ballykinlar in East Down on this board.
Wilson Rooney makes me think that there may have been a Wilson / Rooney marriage in your family.
That marriage at a church in the Shankhill parish, Belfast could point to the family living in a part of Co. Down close to Belfast rather than in East Down or South Down.
Have you had a look at the Ros Davies site? I've just looked and see several variations of Major, McJury ... Majore, Majorie, Majourie, Majury ... there are several other ones that might apply.
If you do a cross check on Irish Ancestors Surname Search for Rooney and Majury you'll see the only place in Ireland where those two names were found in the one parish between 1848 to 1864 was Belfast city. On the other hand if the name was Major the two names appeared in several parishes ... Antrim, Armagh, Belfast city, Derry, Down, Dublin city, Longford, Louth and Tyrone. I haven't even checked the alternative spellings.
Christopher