About place names: this is definitely a short coming of the default mkgmap style file. Maybe Lambertus should send in a request to adapt this in the points style file:

place=city [0x0400 resolution 20]
place=hamlet [0x1100 resolution 23]
place=suburb [0x0a00 resolution 23]
place=town [0x0800 resolution 22]
place=village [0x0b00 resolution 24]
place=island [0x650c resolution 22]

Very strange that villages disappear earlier then hamlets (24 is the highest zoomlevel). Towns disappear already at 22, cities at 20. Resolution 16 or even lower is maybe better for cities.

Íf you are using the typ file, you can modify Garmin type 0x29 (powerlines) to a (invisible) transparent bitmap with the online typ file editor
http://ati.land.cz/gps/typdecomp/ (try Line style: Width=0 px)