for the 1-: try to edit your sys.txt and modify in this section the dpi value
[rawdisplay]
;dpi=auto
;dpi=320
;dpi=480
dpi=560
;dpi=640

for the 2-: you must edit color.ini file from your used scheme and change the value in this section
[roadsign_sprites]
main="street_name_main.spr"
left="street_name_left.spr"
right="street_name_right.spr"
leg_left="street_name_leftleg_dn.spr"
leg_mid="street_name_midleg_dn.spr"
leg_right="street_name_rightleg_dn.spr"
font_color=32,32,32

for the 3-: i don't use vr, not working for french