Travel to Calcutta - Delhi - Agra in July

Hi all,

We are planning to visit Calcutta, Delhi & Agra from Dhaka. Originally
we are flying from Sydney. We know the monsoon season starts in June.
Does the condition get worse during July?

We are planning to stay probably 7-10 days in total and will see the
major tourist attractions. So far we planned to fly/bus from Dhaka -
calcutta, Calcutta - Delhi (rajdhani express), Delhi - Agra (train)
then return the same way. Does any one have any suggestions or
comments.

Sorry, I have asked too many questions as trying to gather practical
experience .

Thanks in advance.

Anu