HelloCustomerand welcome to justanswer.com,
unfortunately there is no easy way to loosen and remove these seals. You just have to be patient and work slow. you could try spraying some penetrating oil on the seals to see if that loosens it up some.
1) yes you need to add rtv to the corners where the round part of the gasket meets the cylinder head (four places)
2) You need to get as much of the old seal as possible in order for the new seal to do its job