How was the relationship between India and Krung SriAyudhya times
pertaining to trade, religion, society ?   What connections did Krung
SriAyudhya have with India during that era ?

Hey, couple of comments:
You'd probably have better luck with this if you posted it under
"Cultures" since it's more of a history question.

Also you can probably find more on the web if you search with the
various spellings, "ayuthaya", "ayutthaya" and so on.  since this is
Thai and it tends to get spelled different ways when romanized.

Here's a short bit on Ayutthaya and India from the Mahidol university
website:

http://www.mahidol.ac.th/Thailand/history/ayuthaya.html

"The Ayutthaya period was early Thai history's great era of
international trade. Ayutthaya's role as a port made it one of
Southeast Asia's richest emporia. The port of Ayutthaya was an
entrepot, an international market place where goods from the Far East
could be bought or bartered in exchange for merchandise from the
Malay/Indonesian Archipelago, India, or Persia, not to mention local
wares or produce from Ayutthaya's vast hinterland. The trading world
of the Indian Ocean was accessible to Ayutthaya through its
possession, for much of its 417-year history, of the seaport of Mergui
on the Bay of Bengal. This port in Tenasserim province was linked to
the capital by a wild but ancient and frequently used overland trade
route."

anyway I know that's not a lot but hopefully it will help you find
more.

Oh, and when asking the question you may want to point out the era in
history & the fact that you're talking about an ancient Thai kingdom. 
I think the reason you're not getting any answers is that people don't
get the question.