F2P botting is not that great anymore, too much of a hassle for so little gp. If you still plan on doing it, runes, feathers, and other stackable non-notable items can be dropped when killed in the wildy. You could also buy high price item (ex: gilded stuff), get a max of 20, and suicide to a mule in wildy.
No. As long as the quantity is 20 noted stuff, the value of the noted stuff doesn't matter which is a big oversight ngl. You can also use non-noted but stackable items such as runes and feathers.