If academics and research are not your strong suits, why do you feel you need to go for a master's degree?  This shit ain't easy and it ain't cheap.

The questions are all good, they just need to be asked to the right people. I suggest emailing directly to admissions, they are paid to answer your questions.

Yeah, you're probably going to want to continue your research a bit more. Your questions imply a lack of baseline research into your chosen degree pathway.

That's ok, but perhaps a little surprising to some of us if you've graduated with a bs in architectural studies. I'd recommend diving into resources like those from the ACSA, NAAB, NCARB, and others. Here's a website put together by ACSA you might start with: https://studyarchitecture.com/

On your question of 2-year vs. 3-year programs ... I'm pretty sure it depends on your degree, courses, and NAAB criteria for accreditation. Most of the 2-year programs are shorter because the students getting into them have degrees and coursework that gets them further ahead on the NAAB criteria. Your bs arch studies degree probably doesn't get you as far and why no one graduating from your school gets into the 2-year programs. 

My M.Arch program was the same process for everyone to get admitted, but I think all the students getting into it from another school were put on a 3-year path. Only the students coming in from the undergrad program at that same school (i.e. the 4+2 pathway) were put into the 2-year M.Arch path. The school could do this because they controlled the coursework in the 4 years before you were admitted into the 2-year program and ensure that in the 6 years you'd cover the NAAB criteria and they could award you the degree. Students getting in from other schools with various degrees could attempt to get recognition for criteria/credits for required courses to shortcut the extra year a bit, but it was always hit or miss. There is little incentive for the school to work with you to figure it out and get you through faster.