Hey Cubano, I am in no position to answer your questions since I am not part of the club directive however, since I am a member of this club I am going to give you my opinion "why probably" to your questions
1= Actually, it is not MMAS (M=Miami) but instead it is FMAS which in my opinion when it was founded (over 50 years ago) it was intended for a much broader area than it is now, therefore the meetings have been planned as centric as possible to be able to entice people from all parts of South Florida to assist and hopefully join E.g. As far north as Boca Raton, Boyton Bch, Palm Bch. Cty. And south, Hollywood, Miami, South Miami.
I think the Fort Lauderdale area is a central area that has a good amount of highways convenient to most of us, this includes I-95, I-595, Fl Turnpike, A-1a etc.
2= Saturdays & Sundays are in my opinion for most people to spend with the family, although this is not my case as I work on the weekends, I am sure my wife would not be to happy if I tell her that one Saturday every month, I am going to go to a meeting at 7:15pm ?, also from pass experience the attendance to meetings held on the weekend tend to be very inconsistent, this is mostly due to the wide variety of event that tend to happen on the weekend more than during the week, E.g. Holidays, birthdays, celebrations etc. therefore, weekdays ensure a more consistent attendance.
I must repeat that these are my opinions only. Hope they helped