Incom from hp

If he is the only child and the property is free from any possible claims, the income will be taxed in hands of the son as you said( i.e. after allowing porportionate deductions)

YES. In case no WILL is there, please follow the link below(discussion on legal formalities):

https://www.lawyersclubindia.com/experts/Transfer-of-property-to-legal-heirs-on-death-of-the-owner-384386.asp