Questions around PCL reconstruction rehab

Hi all,

On 25/07 I had PCL reconstruction on my left knee. It was an isolated rupture. I'm now starting rehab and just had some questions I can't find the answer for online at all. I'm supposed to be 'partially weight-bearing' on my left leg for the next 6 weeks. I'm now 10 days in and find that I am now using my right leg a lot, and getting more confident at standing on it for a while at a time to cook / shower. Coupled with lying / sitting down and having my leg raised all day, this is now starting to cause some issues with my lower and upper back.

1) Is there a limit to how much weight I can put on my left leg? I'm trying to avoid it as much as possible, but should I actually be encouraging it (to a point) because this will help the healing process?
2) Are there any safe stretches I can do that will help with my back? A lot of the ones I've found online relating to hip stretching involves bending the knees.
3) I used to be very active before the surgery and am struggling with being so immobile. Are there any exercises I can do that would get the heart pumping a bit that are safe?
4) Is Foam Rolling the affected leg sensible? Or should I wait for the bruising to fully disappear?

Many thanks for any input !