Yeah, pause is a must have in any game, it own name says why.
Items in walls should return too, also maybe some traps in wall, like they did in Chronicles with these Hunchbacks/Fleamen.
I think that real-time acess for some items can work, but only if optional like in Mega Man so you can change things instantly OR in your inventory pressing pause.
A quicksave is a great idead too, can work like a checkpoint when you enter a area, so if you dies here and press continue you will appear in the beggining of that level like in the classic games.
Thanks for sharing ideas, Im happy that this topic is alive yet xD