Please confirm I will be eligible for 24hrs visa free transit and I can exit the airport.

Yes, you are eligibe for 24 hours visa free transit because your overall transit time in Guangzhou is 23 1/2 hours, i.e. from 19:30 (7:30pm) until 19:00 (7:00pm). You don't have to worry because of possible overstay because only the scheduled times of arrival and departure are counted. So, if your flight to Delhi is late, you are just fine.

As far as your exit from the airport is concerned, you have to apply for 24 hours free entry permit upon your landing in Guangzhou. Keep in mind that is highly advisable to have your accommodation booking done before your arrival in Guangzhou and ready to present it in hard copy. Anyway, although you will almost certainly be allowed to exit the airport, you have to know that the last word always depands upon discretion of immigration official.

Do you have any credible source that Indian passports can take advantage of this facility and indeed exit the airport because my travel agent is convinced that I will only be confined to the airport.

Indian citizens are definitely and without any doubt eligible for 24 hours visa free transit in China and the most credible source for this claim is TIMATIC, the real source that is the beginning and the end of every aspect of the entire air traffic in the entire world for every citizenship. As far as your exit from the airport is concenred, I have already written that your chances are good, but that the final saying is one of immigration official. Honestly speaking I really don't have anything to add.

Thanks. The China Southern website is extremely vague so very difficult to understand if I will be allowed to exit the airport or will they find some loophole to prevent me to do so