For the items I was referring to the fact that item drops take 5-15 seconds to appear when on certain screens. To me that just seems rude to make players wait around for an item that might not even show up. It kills the pacing and it is just boring to do. Also for the discard system since you mentioned it I do have an idea. Instead of dropping the item just do it like an adventure game. Go to your menu to click on the item you want to use . Then it takes you back to the game screen and you cursor changes to the item's appearance. After that you just click on what you want to use it on. If the item does not fit where you click just make a sound effect that indicates that and vice versa if it does.
For the part about matching I strongly disagree. Most players will be able to make many matches just by swapping as quickly as possible which in turns builds up combo very fast. In fact I would ask you to play your game when you get the chance and for one battle focus on speed matching while not using the multi swap mechanic. Then do another battle only making good multi swaps(almost every swap rewards mana) and I want to know what you feel is a better way to play. I would also ask that you tell how often you drop your combo when playing both ways. From my own play I was not able to get my combo high or keep it going reliably while trying swap multiple pieces at the same time. On the other hand I had no problem consistently reaching 100+ while just moving 2 pieces quickly.
I am not trying to offend you I just think it would be a good idea to settle on one way of play so you can build upon that preferred style. To me the ability to link multiple pieces together and swap them all at once is too slow a way to play while at the same time you are playing a shoot em up. Playing fast just makes more sense with how frantic this game can get.