HCG Dosing Duration and Mixing the Solution

Hello!

Can someone clarify me about the HCG?
I’ve read forums about it but there is so many different things told about it so i’m not sure about it at all…

I’m doing 12weeks (maybe extend to 16weeks) Test E 800mg/week droping it to 600mg/week last few weeks.

So what i need to know is;
-How should i dose the hcg and then how often per week?
-When to start taking it and when to stop (for PCT)?
Then i can only get solution at 1500ui or 5000ui vials per ml. How do i mix it and with what?
-Then again is it so neccesarry to take it or what are the differences WITH and WITHOUT HCG (time hormones and everything get back to normal)