well traditionally, i believe cutting the cake sort of signals the end of the night so if you cut it sooner, you don't want people to leave, right? or at least in gora weddings it does... but what you said about desi weddings is very true. it makes sense to cut it before dinner and serve it as dessert or part of dessert.
you've given some great, common sense advice re: photographers. do you have a folio somewhere? i'd love to see your pics!
In Gora wedings the cake is mostly cut before dinner, cutting the cake kind of finalises all the ceremonial parts to the wedding before you go onto other things, i.e dinner and dance.
I do have a portfolio, which I can try and PM you a link to look at, give me a few days and I will get it sorted.