Architecture Design, Interior and exterior

Sorry if i posted this in the wrong section. So i’m needing help and hope that someone would be able to explain this to me. So when making a enter-able building would it be better doing each wall separate from one another or all of the wall connected together in a whole. My second question i make my buildings within AutodeskMaya and i’m pretty new to making buildings and so far with a lot of practice and aloooot of failure i am getting a little better.

My real issue comes just from texturing the walls perfectly, i’m still learning the engine but i’m going to try and make a seamless brick texture for it and just use a textercoord, and multiplier to try and make it fit if i can but that will be later. Right now i am needing some opinions on separate walls, ceiling, roof, floor etc. or should i do it as a whole. I am trying to get the same quality as (I hope this dose not make anyone look down on the topic but i feel like some of the graphics are pretty nice, but that is my opinion) Watchdogs. That or even some of the houses within The Division.