Even though it is a hot water pipe, you still would want to leave some of the area around the pipe with less insulation. Heat gets turned off and you get a massive cold spell and oops. I realize it may be unlikely, that's why you get to make the decisions, you are there
As for that pesky floor joist, it is close to the outside wall, thus if it disappeared no one would notice. But rather than removing it (I know I'll get yelled at) I wouldn't hesitate to turn it into a 2x6, or at least some of it too gain access. It somewhat depends upon what is above, hot tub or empty wall space. I have a similar pesky joist which I'm closing in on and it will meet with the jig saw at some point.
If 2x6 is too drastic, then 2x8 with a sister. (Why are they called sisters?)