Usually when a girl registers in some marriage agency, she has a photo shoot (for free). Agency hires a photographer, so the style of a photo shoot depends on him/her. Sometimes girls even get clothes from a photographer or agency.
Mostly if you find a profile with bad quality photos, it means either that there was no free of charge photo shoot or that there was a bad photographer.
Yes but there could be a good balance of both: studio photos with the girl looking her best and photos taken with the mobile phone in the park or at home watching TV.
After all I think that the girls mostly want to look their best in studio photos with full make up, etc but many want to show thrmsleves in real life situations, especially when they do not get the studio photos for free.