Migrating from Antlr 2.7 to 4.7

[Antlr User]

I am looking at Antlr 2.7 grammer from which parser/lexer are created for C# target. This is working for .NET framework 4.6 and Antlr runtime 2.7.2.10.

Now, I want to migrate to the later version for Antlr v4.7.1. I am new to Antlr and have the following queries towards migration.

     1) Are the parsers/lexers generated with Antlr 2.7 compatible with Antler runtime 4.7.1? Can I just move to latest runtime and not face any issues?

          - If the answer to the above question is 'Yes', then assuming there is no change in the grammer, is there any benefit I will get by moving to Antlr v4.7.1?

          - If the answer to the above question is 'No', then assuming there is no change in the grammer, can I use the same older grammer (.g file) to generate the parser/lexer with newer version Antler 4.7.1 and use with this newer runtime? or Do I have to re-write the grammer file again for Antlr 4.7.1?

      2) Is there any quick starts documentation that would help me with the migration?

Any help would be greatly appreciated!