Re the fuzzy screen, I think you might just be finding the resolution limit of the garmin. Compared to what we're all used to with modern mobiles it's pretty woeful to be honest! It is however fit for purpose whilst using the 1:50k maps, I've read that it can be an issue whilst trying to see the detail on a 1:25k map. Can't personally comment on that though as I find the 1:50k sufficient for pretty much every where in Scotland other than maybe the Cuillins.
With regards to zoom range on the map, the unit does default back after you zoom unless you bring up the pointer with the directional keypad. It will then stick to whatever zoom you select.
It has a secondary effect of no longer autocentering your position on the screen though so your position will move, ie the annoyingly large blue arrow will move. Rather than unit keeping your position central and moving the map with the blue arrow remaining central
I like the gpsmap64 but like most garmin products it takes a little bit of time to get used to
