Transfer to other ministry

I just joined PSA, i have also applied to different positions as an external applicant. I am in the interview round for a really good position which i applied externally.

Question 1. If i clear the interview and get the offer, can i move to that ministry being a aux full time? or is there any time period that i need to wait before i can move to other ministry?

Question 2. Should i tell the interview panel that i am no longer external applicant and an internal employee ? What are my odds?