James you are surely on your way to good health! Keep on going!!
If I were you I think I would slowly work up to 1/2 hour on the rebounder and maybe the same on the bike. As you are able just a few reps with very light weights. I would suggest you increase your reps not the weight for a while. The rebounding is very important!
Let us know how you are doing! Come for a visit now and then. This forum is an awesome support system. Welcome.