Competition wherein one is charged a fee

Q: I will be hosting a car show during the course of next month and would like to find out if the proceeds from this event can go to a sponsorship for a hajj fund for people that have been accepted for hajj this year. The funds raised on this day will come from the entrance fee that each person pays to enter their vehicle. At the end of the show, the participants will receive trophies. Please advise me in this regard.

When does iddat of talaaq commence?

Q: I've been separated from my husband since january 28th and have only received my talaaq papers in march. I recently received a proposal and wish to persue it. I am sterilized and can't have babies. Can you advise me on when my iddat commenced? Is it from the time I physically / literally separated (28 january) or from the time my talaq papers arrived? 

Seller claiming more than the agreed upon price

Q: A certain person owned a property that his friend wished to buy from him. On seeing the land, his friend offered him R1.2 million. He told his friend, “I don’t know the value of the property. If the value is more, you must sort me out.” After a week passed, the owner still hadn’t checked the value, but concluded a deal for R1.2 million, even making out a contract and signing the papers. A few months later, the initial owner learnt that the value was R1.5 million. He now wants to claim an additional R300 000 from the seller. Is this permissible?