Hello
Nice to meet you, Your scope is very clear and specific, I think is a long project, and the use of BIM is excellent for control of the construction and later when the house is used, for maintenance, I place an amount and a time to developed the project, but is necessary to especificate the surface of the land and the surface of the house for a more precise offer, We can help with the changes in the design that you specificate.
I'm a architect with a lot of experience in the design of houses and the use of Revit, I'm working in a team with my wife, She is an architect same as me, You can see our profile and watch some examples of projects and I can share with you examples more complete of my projects, I can modeler Revit files for architectural and MEP, (plumbing, electricity and mechanical), all of this systems can be placed in the model and the other modifications that you indicated in the scope.
Any questions please contact me.
Best regards
Mario