How did modern hinduism emerge?

I as a indian am curious about the origins of hinduism

We know that vedic religion was precursor to hinduism

What did the vedic people's called their faith?

What are the equivalents of lord rama and lord krishna in other indo European religions?

What was orign of lord rama and lord krishna some say they weren't real and were probably some local deities if so what inspired such long stories especially of their romances?

And how did the 10th mandala got added to rigged much later without causing a mass upheaval of some kind?