what tacking angle should i set on my tacktick please?
Leave it at 90 degrees
The one that means you get the same number on the display on both sides - it depends on the weather conditions.
Leave it on 'Compass' rather than 'Tactical' then it doesn't matter.
I spent time fiddling around whilst waiting for starts at some event a while back and came up with 75 degrees. However, it is always wrong, because the conditions are always different, so I returned to the old faithful of remebering the number on each tack.