You can probably get that answer rather quickly if you gave the administration a call.

Like all the previous portfolio comments directed your way, you need to show progress and design work, not just shiny renderings. The buildings are pretty bland TBH.   

Most schools allow some amount of academic leave - but how much leave you can take without having to reapply varies by school.  There are some at which it's limited to 1 year under all circumstances, others where it's limited to a year unless you can document a medical reason, others where it's 2 years, and others where there's no limit and once you've been enrolled there you're considered eligible to rejoin the program at the point at which you left it, forever.  But in the last situation if you waited for several years you might need to spend more time to complete your degree because of changes to the curriculum.

Hmmm honestly I'd rather that you finish the 3.5 years first. Commit to that one main goal before you pursue other things. Maybe take internships in between terms or do small freelance jobs on the side if you can (if your reasons are to gain experience or earn extra money, etc.). These are opportunities for you to exercise your skills and stuff, but avoid giving your all into it because your one main goal, which is to get that MArch, should still be your top priority. Otherwise, if you see yourself taking a leave of absence after a year of MArch, then eventually deciding to come back after 2 years, might as well take a one year MArch program (common in the UK and Europe than the 3.5) then find work thereafter.

I heard some schools in Europe (Angewandte, although they don't have a bachelor's anymore) allow that, especially those with free tuition.  You can take 10+ years to earn your bachelor's degree if you wanted by taking years off between each semester.