Purchasing shares in a property rented out to a supermarket with a liquor department

Q: Someone has purchased shares in a property that has been rented out to Checkers. Will the rental income derived from this property be permissible, bearing in mind that Checkers has a liquor department within the store? Someone said that since the majority income is from other permissible items, the rental income is permissible. Please clarify.

Cancellation of a transaction upon a specific time limit

Q: I want to sell a piece of land. The total price is R1.5 million. The buyer will pay me a 33% deposit as an upfront payment and the rest within 6 months, and then only will I hand over the land papers and land to him. If the purchaser fails to give me 67% within these 6 months, the sale will be cancelled and the purchaser will lose the 33% deposit. Is this clause permissible (forfeiting the initial deposit)?

Selling sweets for a madrasah

Q: I am standing at a stall in a madrasah and selling things for the madrasah such as sweets, etc. The items do not belong to me but to the madrasah. Can I purchase items for myself from the stalls, or would this be impermissible since I would, in essence, be the buyer and the seller at the same time?