The specialty will not effect ticket sales, just the lvl. (ie. lvl 5 sells more tickets than 3).
Crowd involvement supposedly improved home performance, national appeal, away. Yes
Personally, i would value National Appeal more than Crowd involvement as I would like to think of myself as a top half team, and therefore think it could make the nessesary difference to win the improtant away games, and the conference.
If you are a team struggling to stay in the division, i would recommend Crowd involvement so you at least have a better chance to win your home games.