Everlasting
Everything stays.
Uh... I guess it depends on how much characters you use. My gold remains around 10 000 most of the time. And now I have to find a way to get some promotional items, since I need Neimi, Ross, L'Arachel, Joshua and Knoll to promote and I don't have the items to do so...i dont know i've got a bunch of cash
it just flows very quickly
i dont really buy promotion items at this point (chapter 15) though
And that is not considering the weapons I have to buy, which I truthfully need.
If you want to grind for gold, I believe there was an RNG trick that lets you find a Rune Sword as a drop item in the Tower of Valni around 50% of the time, though I can't remember what the trick was exactly and it is a little tedious.
Also, I just can't bring myself to sell Runeswords very often because I just love them so much. I've got a hoard of them in my most recent SS playthrough.
I've read about this trick and tried it out. It's overly complicated and it did not even work for me, so I kinda gave up. Still trying to dig up some trick to get more money.