To answer your last question first, yes. Yes, you will be injecting the testosterone propionate.
From what I have gathered so far (and please wait for others to chime in before doing ANYTHING - I am very new but have read a lot, so I could be wrong), the suspension in which the Test is found is irrelevant to its effect; the suspension simply controls how fast the Test is absorbed by the body (aka, its half-life). Test-E and Test-C are loved due to them having a very convenient half-life, so after 7 days the body has absorbed half the amount you injected and half remains. In another 7 days, it has absorbed half of what is left and a quarter of what you injected remains. If you graph our each injection, you will see how long it takes for the body to reach a more or less steady state where it is always absorbing about the same amount. Most people inject at half the half-life length to aid in reaching that steady state faster and keep the rise and fall in the amount of Test far smoother.
So if you do Test-P, you will have to both inject more often AND reduce the amount you inject accordingly. Articles on this site who Test-P has a 4 day half-life, so most people would inject every other day. Many on this site say not to go above 150mg a week to start with until you know how your body is going to react. The way to know how it reacts is through blood tests - GET THEM!. So if you are going to take 150mg per week, and inject every other day, you would be injecting 42.86mg every other day. Rounding down to 42mg gives you 147mg a week and rounding up gives you 150.5. Personally, I would round down to be on the safe side.
The pinning for first go might be intense but you do it with small gauge 25G
