I like my new Garmin echo 94sv also. Also liked the closeout pricing since they came out with the echo plus (with touch screen). Didn't want touch screen anyways.
You can use the free Garmin software to type in all your waypoints on your computer and load them using an SD card. Later you can transfer them from the unit back to the computer to save.
I was able to put the same waypoints onto both of my Garmins. Absolutely love being able to do all the data entry on the computer instead of thru the unit's Menus and buttons.
I didn't flush mount anything cuz I like using that space as a cubby for cell phones, sunglasses, and bags of chips.
I've done a 1/2" starboard dash before and it really is easy. Woodworking tools work fine.
Use a table saw with plywood (fine tooth) blade for clean straight outside cuts.
When drilling be careful , clamp the piece because they make curlys and the bits grab at the end.
1/4" round off router bit.
Inside cuts can be done by drilling corners and using a jigsaw IF THE CUT WILL BE HIDDEN by the overlapping flange of whatever you mount in the hole.
For a clean inside cut like that door in the pix, you need to use a router and template.
Hole saw bits tend to melt the starboard