Gathering players with two roles is definitely doable. The ones with three roles... if you happen on them in the Auction, that would be quite a battle hah.

The types of players that your Club requires depends quite a lot on the formations you feel comfortable with using. I've personally have been running with the same squad (minor change in the line up ever season when it comes to transfers) since april. Took me some auction sniping and getting up at inhuman hours to find great players but... damn am I proud of the team I was able to gather! They are getting old now though... sigh I'll have to start looking for new stars. T_T
But we've had a great run! ^_^

Anyway, playing your team with around 14 players is definitely doable and nothing out of the ordinary AND gathering players with 2 roles is not that hard. At least with me, since I don't use too many different formations, 2 roles is quite adequate.