So I use my binding keys on my wacom tablet and I could use a little help with setting up two functions. One is the zoom wheel. Right now when I use it it moves in discreet increments of like 25 66.7 100. Is there a way to change it so it doesn't have set zoom presets?

Also is there a shortcut key I can use so I can easily just click to get the hard eraser? I understand the toggle brush function for the brush/eraser but sometimes I just need a hard eraser instead of making my brush the eraser.

If your pen have an eraser side you can select the hard eraser with it. Every time you switch to the eraser side, Krita will select this preset for you automatically, and as soon as you switch back to the pen side, Krita will switch back to the preset selected before.
There are no way to assign a shortcut to a brush preset yet. It may be possible when python scripting arrives, but i'm not sure about that.

Smooth zoom, as far as I know is not possible with keystrokes. You will need to use ["Key press and hold" + (mouse or pen) drag up/down], or touch gestures.
By default [CTRL + Middle Click + drag up/down] will zoom. You can set it to Middle Click + drag up/down so you don't need to hold CTRL

Does your pen have side buttons? With my pen on Windows, the secondary side button + CTRL activates zoom mode by default. On Linux it's the primary side button + CTRL.

Thank you so much! My pen only has the double click button, but I think I found a solution to my issue. I really appreciate the fast reply.