Master Thesis research Proposal questions

I have no idea how this works so I'll just post my questions ^^.

What is meant by "validation study"? The way I understand this is to first check construct validity and reliability of a given model in a different population. Is this correct?

Secondly I have the following data: Original research questions from base assessment model, confirmatory factor analysis in population A, correlation results in population A, descriptive statistics in population A.

Third I wanted to know if comparing the confirmatory factor analysis results of study a (base study, which developed the model) with my CFA if I were to do one to check the construct validity in Population B is possible and if so, how?

Fourth how do I test for reliability?

Is it possible to test for internal validity in SPSS and if so, how? Kind Regards, Maximilian Kerski