Multiple actions come from things like black rabbit ring (best and you can equip multiple), mystery of the night, two face shield, or duchess covenant. You cannot take back actions (not without a bug anyway and I'm not 100% on how it works).
Weapon swap is just choosing the equip option in battle, below run. You can swap whenever you want but the weapon you are wielding when you choose your last action for that turn is the one that will be used for your actions, so for example if you had butcher's axe equipped, then all your attacks would have double damage against bleeding enemies. Or if you were using black goat's ring (so you have 0 mp), equipped wand of creation to cast a spell then swapped to something else, when you try to cast that spell, you won't be able to because now it costs mp since you swapped away from wand of creation. You can use a weapon's skill and swap to another weapon and the skill will still work. If you choose attack while wielding hans, but switch to another weapon you will not get the +11 extra hits though since the 11 hits is a stat on hans and not a modified attack like say god's angels, mary's wand, or miranda's axe. Weapon swapping is a free action, just like using a healing item.
install the rpgmakervxace rtp.