Hollow
They are hollow-use a couple of self-tapping screws and you are good to go. Some folks just use a lashing up there-eliminating the need to drill anything.
As for jumpers on this mast-it is WAY to strong to need jumpers-they would just add windage and weight. Jumpers generally add fore and aft support, while the spreaders support the rig side to side.
If you have trouble sheeting your genoa in because it is hitting the top spreaders (they should be touching when trimmed all the way in), the first thing to do is be sure the lead is not too far forward... If the lead is correct, then the problem is simply that the genoa is built with too much roach. Have a sailmaker add a little more leech hollow, and the sail will fit just fine.
If you are really lazy, just don't trim in so far!
Cheers,