m12

2 people can lift it easy... one can do it as well

unless you measure them very carefully, replace them

there is a tensioning rail... but not during the head removal. You are only looking at removing the upper guide rail

hood... totally unnecessary

it needs machine work if you know what to look for. If the valves wiggle in the guides its the biggest giveaway. I think most people who have done these heads will agree its not common for them to warp or crack.