GPS Waypoint coordinates

Actually - that means that your "successfully" entered values may be way out - you would have entered deciaml degrees with the decimal part less than 0.6, and your GPS would have taken that as minutes. Just set your GPS to dd.ddddd and re-enter all your waypoints.

Yes - some of them, at least. The list at the end of the "Driving Notes" section is in dd mm.mmm, while the "Waypoints" section is in dd.ddddd. You'll need to change the format in your GPS for each of those sets. Just look for the "space" between the degrees and the next value - if there's a space, the next figue will be minutes; if there's no space, then you're dealing with decimal degrees.

You have to be careful: if you type in 23 50, your GPS may interpret that as 23.5 degrees, or 23 degrees 50 minutes, depending on the format you chosen in the GPS. That's a significant difference on the ground.