Evo 74 2006: how to trim it for an easy ride in the chop?

[Karen]

I have just bought an Evo 74 2006 which I have ridden twice up to now.

Most of the time I intend to use it with a 4.2m?? and 3.8m??.
Sometimes with a 5.0m?? and 5.5m??
My weight is 62 kg (+ 6 kg (dry) neoprene/trapeze etc.).
Normally I sail on choppy water (Grevelingenmeer in the Netherlands).
I realize I must put more front foot pressure and adapt a more straight standing up style with a wave board (I am used to ride the FF-138 2004 and the Kombat 96 2006 with the freeride fin only).

When I ride the Evo, the board tends to put the nose into the wind all the time until I finish in the water if I don't take care. The same when I am entering the rear footstrap. For the rest I realize that it is a very stable board, even with the 5.5m??.

My questions:
Which fin position for an easy ride in the chop?
Mastfoot position? What is meant by the middle of the masttrack: the masttrack included the lengt of the "hole" where you enter the mastfoot or the length of the masttrack without the hole?
Which type/length of fin can I buy as a second fin for the 5.5m???

Karen