House texturing problem

[max2012181555]

Hello

I'm trying to make my modeled house ready for Unreal Engine. the problem I'm facing >> I get low resolution texture for the big parts in the house like walls and floors. for now I've Combined all object that won't be animated to one single object and I'm putting all UV shells in a single 4096 UV.

I've two Questions:

01- What is the best way to make this Building ready for game engine with moderate RAM cost and High res Textures? is it about exporting every peace alone or what?

02- While I have DOOR and Window for this house, I'm not suffering from low res. but should i make them share a single UV map with one material Like Screenshot Below to reduce ram cost or export each one of them with its own material and based on it's own UV map?

Thanks for Help and time for reading and Reply