Thank you for the kind words!
I brought Milo home last night and he is as happy as a clam! Eating like a champ, lambchop-ing, taking some laps around the living room, begging (of course) and loving all the extra scratches he is getting. I can tell he is tired but otherwise he seems fine thank goodness.
I mentioned the diuretic to the vet and she didn't outright dismiss it but mentioned it is more of a heart disease treatment rather than what Milo has. I also think she is cognizant of the fact that before his chest was drained he was basically suffocating and I don't think she wants to let me get too excited about prolonging life if it means suffering. This is of course, the very last thing I have on my mind--I just love him so much that I want to keep him with me as long as he wants to be here! Interestingly enough, this is the first case of thymoma/mass she has seen in a bun and she is one of the HRS recommended vets too! Lucky Milo :/...maybe he should buy a tiny bunny lottery ticket.
But, to all of your points, I will keep an eye on his activity and pain levels and if need be, can treat the symptoms as much as possible that way. I just can't process that a bunny who is so into eating and drinking and exploring, even with the breathing difficulties he was having, is ready to move on.
Milo is the only bunny I have now--but he and his sister Ella have given me a LOT of medical experience over the 8+ years since I adopted them--E.Cuniculi leading to head tilt and Motility/Gas issues the main ones. So I am now a well-practiced bunny whisperer.
Will check in with the vet today(and going forward) and let you know if she has any more advice!