Hi there
The nerve damage can go on for a while after you finish treatment before it starts improving, but it will. My oncology nurse suggested vitamin B, and my hands and feet (my feet were really not good) started improving immediately - but that could have been pure coincidence. But unlikely to do any harm to try it.
Not sure about nails - my finger nails were fine, except they went a slightly brownish colour, but hard to see. My toenails went black, brown, grey, white, and split but none dropped off. Took a long while to regrow but eventually all of them returned to normal.
I do have lymphedema (left arm only), but haven't experienced that leaden feeling - I do have to keep working to keep fluid from accumulating. I massage my arm, and have a regular professional massage too, but I find exercises (your physio should be able to help) and a pressure sleeve are very effective. No-one wants a pressure garment if they can avoid it, but having worn one now for over three years, my arm looks good, feels good (no weightiness, pain or loss of strength) and so I feel it is effective at maintaining a good condition.
Good luck, best thing is that chemo is over so things should improve, but it's hard to be patient!!