How to install SSIS on SQL Server 2014?
The SSIS intallation is working as a charm, the only problem was that we wanted to connect to SSIS 2014 from SSMS 2012.

At the end we agreed to upgrade the developers machines to sql server 2014 developer edition, and migrated the packages to sql 2014, and now everything is working fine.

I will leave the question here as a reference, for the community and for myself, because at the end I had so many problems, and they all have been solved.