re: 180% headsail question
Unless you have a split pulpit/lifeline arrangement sheeting outside is going to put some strain on the lifelines and stanchions as the sail is forced over and down again. This is esp true if it's an old 'deck sweeper' headsail.
Sheeting inside will be cleaner, but requires someone going forward to 'skirt' the sail back inside as it will tend to blow outside on the tack and usually hang up on the first stanchion. I don't think the visibility issue is much different either way if the sail is fully sheeted in for upwind work.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)