1.)
It's possible it will very slightly detune it in either direction. It won't be much, if at all.
2.) Solder every electrical connection. But, looking at the QFH antenna, I can't see why you would connect rwo connectors?
3.) Buck up and stick it to your roof anyways :^).
Since you're trying sat work you'll want it to be maneuverable. Just aim it out the window.
If your doing local work, just make a 1/4 wave with ground plane. You'd be surprised how many people don't care about antennas.
http://fucimin.altervista.org/en/groundplane.html
Another simple antenna is the slim jim, it has the advantage of having a wider bandwidth http://www.hamuniverse.com/slimjim.html
It's also harder to see.
Picture related
Mount it to a block of wood for the appropriate pitch of the roof. And mount it to the gable of the roof. Paint the wood/ant. the same color as the cable. Staple the coax near the frame of the house. Use spraypaint to change the colour of the coax. Pretty stealth.