Well since you can not really control the direction of which your C-130 would come from (at least I don't know how to solve this, since OCL's are spawned "outside" the map), you could just make it a drop zone instead of an airstrip. Pretty much like the US supply drop zone. This allows the C-130 to approach from any direction resulting in better optics
Altogether you should use the DeliverPayloadAI with a combination of the existing PARATROOPER special power and that of the A10 (to get the "diving"). When combined carefully you should have a diving C-130 that drops some vehicles etc. onto your drop zone and then flys of the map.
IF this does not work you could use crates that upon impact onto the drop zone grant soldiers / vehicles what ever to the player.
For your second question, I never tried it, but it might work. Just add the approriate lines to your soldier's commandset, however I don't think you can deactivate the image on the side of the screen and since you want it to actually show the reload time this would be pretty much impossible. For the viewing distance, maybe NEEDS_LINE_OF_SIGHT could be a good way.
And finally a slot limit is possible, of course.