For map i recommend use HERE Beta for android if your phone is android.It free and offline lifetime navigation.They update the map 2-4 time a year.

For prepaid line i recommend use maxis hotlink.3g coverage is excellence and speed also good 1-5mbps.
I'm use #hotlink prepaid.It come with free basic internet 64kbps speed.Just need active line to use this and good enough for whatsapp and lite google search.Need more speed 3g or lte subscribe daily,weekly or monthly.