Mast... sounds like you have water in the mast. Not all masts are the same. A comptip equiped mast will be heavier than the "old" type of mast. There is a chance that the foam plugs might have absorbed some water (explaining the weight and the lack of sloshing sounds). Find the area were the mast leaks (search old posts for that tasks) and fix it.
EVA... yoh! this is how it goes... not much you can do about it. Replace the stuff when it is due. I use a 3M product which is less grippy but more resistant to wear. Some people use neopren or carpet... nothing lasts forever.

Patrick