Your second question has nothing to do with the Revit API, so it would be better to ask it in a different forum.
Please note that this discussion forum is dedicated to programming Revit using the Revit API.
Therefore, you cannot expect an answer to a question such as yours relating to installation, product usage or end user support issues here.
You should try one of the non-API Revit product support discussion forums instead for that:
https://forums.autodesk.com/t5/revit-api-forum/this-forum-is-for-revit-api-programming-questions-not...
The people there are much better equipped to answer your question than us programming nerds.
However, I'll respond with what I think anyway:
> Is it possible to create a project using a structural template and a building template?
No, a project can only be based on one single template.
However, you can set up the template yourself in any manner you like.
Therefore, you can combine the architectural and structural aspects of your choice yourself into one single template for your specific purposes.