I just got Minecraft for my Mac. I sadly have a few problems with the game. First is the lag. It will lag to the point of when I try a command, it seems to be a few seconds off. When I try to move my character or make them jump, it's the same way. I tried to figure out the problem by looking at my Java as well as the Minecraft game. They both were up-to-date. Then I tried to see if exiting out of all of my browsers besides the game would help - it didn't. Not too sure what's up there....
Another problem I seem to have, is that I cannot use objects in my inventory that way I would hope to. For instance, I cannot build a building or create a crafting table. A better explanation is that if I have any wood that are grouped together, I can't split the group apart to create wooden planks; I have to have two different groups of wood just to be able to.

I love Minecraft, but I am frustrated by these problems I seem to have. Can anyone help please? I don't want to have to not be able to play the game. :(