I don't know much about softball scholarships, but here is what I found via google:
Looks like 12 full scholarships is the answer
http://athleticscholarships.net/softballscholarships.htmhttp://members.tripod.com/~willett/softball/cathyaaolchat.htmlThere's probably more "official" information at NCAA if you can navigate their site.
Thinking about vball...the number of players a team has probably depends on budget and the coach. Some coaches are willing to take a lot of walkons or even have just practice squads. Some coaches don't want to have too big of a team to manage. It always helps if you already have another scholarship lined up (academic, 4-H/FFA, etc.) to allow you to walk-on.
A&M's softball team seems to have @ 17 on the roster.
Not sure if this is the kind of info you were looking for. Hope it helps.