Two more things, you can't trust a fretted fingerboard to be true once the frets are off (or even before), and you have to lower the nut to account for the missing frets.
I agree you should buy a cheap fretless first to see if you take to it, but don't let us scare you off if you've got reasonable woodworking skills. Assuming your Yamaha does not have an ebony fingerboard, you're best to put epoxy on it to prevent wear (use West Marine epoxy only). For the fret slots get some wood dust slightly lighter in color than the fingerboard and mix it with epoxy, fill slots, wipe excess & allow to set, easier than wood slats and looks fine provided you epoxy the whole fingerboard after. If the fingerboard needs planing you should do it with slots filled. You can have a luthier handle any step along the way, best to have one do any necessary planing.
SVP-CL + IPR 1600 + SWR Goliath III 4x10 = bliss