My father (senior citizen - aged 70), who is living with little over a year had his PR card expired last Nov (nov 2010). He has not met the requirements for renwal (730 days) yet, but he will meet the requirements by Jan 2012.
His passport is also expiring in December 2011. can he apply for the passport renewal now with the expired PR card, which he can not renew till Jan 2012?

due to unavoidable circumstances, he needs to go back now for a couple of months. is there anyway he can come back (e.g. with the travel document)?

Any help will be greatly appreciated.

Yes, You can apply for renewal of Indian passport as long as you have the original PR card.