You would probably be placed in a 3.5-4 year masters program for Architecture at those schools since your Bachelors isn't a pre-professional architecture degree. Most of them have an application pool and if you meet the minimum (usually a 3.0 gpa, 1000 gre) they will place you in the pool and select from there. Selecting students for architecture is less about the numbers and more about if they think you will fit and succeed in the program. (statement of intent, recommendations, portfolio)
The amount and type of work needed for your portfolio varies by school but shouldn't be too involved since you would be basically starting over in architecture, but looking at the portfolio requirements on the admissions page for each school would help you. They should have a section on what they require for the non-architecture undergrad applications.
I know for the University of Florida they would put you in the 4 year Core program which 2 years of "undergrad" courses (basic design studios, history, structures, etc) and then the 2 years graduate program. Most schools have similar programs but the timeline differs, but they all focus on acquainting you with architecture before throwing you in the fire.
I would also recommend researching what the schools' design programs focus on (technical, research, design, technology) because that can make a huge difference depending on what you want to pursue as an architect.
Good luck!