Using SQL Server CE and SQL Server Express

I have an app which currently uses SQL Server CE, and the sch开发者_如何转开发ema is in a .sdf file. Now we want to allow it to connect to a SQL Server Express edition based on some mode.

I have a couple of questions:

1. Will the Linq-to-SQL files (generated by sql metal) be the same for the both the databases (apart from the name etc)

2. Can we use the linq file generated for .sdf, and extend it for the SQL Server Express, and override any DB specific things there? Or is it not advisable to mix both of them ?