Guys I need a lil help with the hCG.

Questions:
Can I buy bac water at a pharmacy or need px?
If i mix 5000 iu into 2ml of water then each 0.1 is 250 iu, is that a good amount to shoot every 5 days 0.1 ml?
Is a 30 guage 1 inch insulin needle sufficient for this? do I have to shoot it IM or can I just do it in a stomach fold? pinch fat and plunge it there
How long can it stay in fridge mixed, do I need another sterile vile to do the mixing? can I get that at the pharmacy too?

sorry might be some simple questions, this is my first time using hCG, I tried googling but find varying answers for everything