Atlantis,
sorry to hear about your losses in your previous posting. That’s frustrating on top of heartbreaking.
For the java moss, you can take the whole clump out and rinse it gently in a bucket full of clean water just removed from your tank it you like. I also find that some organic mulm tends to build up in the moss, but mostly I let it be. Keeping processed food feedings to a minimum and using mostly live food helps keep down the waste as well.
As far as vacuuming the gravel, some eggs and new hatched fry may have to be sacrificed for the good of the rest of the tank at weekly cleaning time. But if you take care of it often, and aren’t sucking up clouds of accumulated brown goo (always an indicator I haven’t been doing my job frequently enough!), then it is fairly simple to let the waste water settle in the bucket for a few minutes and just visually inspect for living beings and remove them before dumping the old water down the loo.