i was actually just thinking about inertial forces acting on antimater. technically it should still have mass since mass as we know it is calculated as an absolute value. so gravity and inertia should affect a coherent mass of antimatter as it does matter.
as far as containment goes, the only thing i could think of would be to use super conductors to generate a strong enough magnetic field, but then we would need to have ambient temperature super conductors, and that's a whole nother topic. the ideal situation for containing and utilizing antimater would be in space. as a weapon, there would be less likelihood of a contamination, and as an energy source.. well... you could get rid of it fairly easily should containment fail. the most ideal containment method would a series of hyper-magnetic materials that required little to no electric current to maintain a stable field arranged to create a bubble around the antimater. a detenator would be a moot point in my opinion... just point the damn thing at whatever you want to destroy and fire... impact will take care of mixing it with the correct amount of matter to release it's destructive potential.
and just because i love to do it, it is theoretically possible to have an entire solar system.... or galaxy for that matter (no pun intended) created out of nothing but antimater. since it should theoretically behave exactly as normal matter, fusion should still occur just as it does in the sun and give of exactly the same amount of energy. i wonder if there would be any real way to detect such an existence without finding out the hard way.
another question that should be posed imho, is how much energy do you think spacetime could technically support before something funky happens? honestly, 270 megatons is a really big number, especially from a 1kg catalyst... what would happen if you used, say, a 1 metric ton catalyst? 100 tons? how high could the energy release go before the normal laws of physics would begin to skew... till the fabric of spacetime begins to warp? eventually something would have to happen that would be interesting.