New server and going from no source code to source code - Is it possible?

My current database is version 3.9 with no source code.  I want to move to a new server and would like to switch from no source code to source code at the same time.  Once I've completed a fresh install on the new server is it best to restore or import my existing database?

Once that is done can I then upgrade to 4.0, 4.1 and then 4.2  using source code if my existing database does not have source code?

The website does not usually utilise the source code version. The Source code version is used in your development environment using Visual Studio. When you built the source version it creates a no source version which is then published, maybe to a local directory and then uploaded to the production website. This can happen in various ways and you need to have some experience with visual studio to carry out this process.

Regards your database and install. The database version needs to match the version of code running on the website. If already have data in the current database which you want to keep it then you can upgrade the database from version 3.9 to version 4.0, version 4.0 to version 4.1 and finally version 4.1 to version 4.2. Alternatively if there is only a little bit of data or minimal configuration maybe it is best to just run the install on the website and create a new version 4.2 database and then manually setup products, etc. Or as you say you can export data from 3.9 and import data to 4.2 using the respective version excel files.