Hello. Thanks for mapping. 
About the use of the tag 'service' road
This is what the wiki says
"highway=service 	Use only for single laned roads used to access highway services such as fuel stations"
See this wiki
https://wiki.openstreetmap.org/wiki/India/Tags/Highway
Most of the service road you have mapped as access to a group of buildings should be tagged as residential in urban areas.
Best regards