Valid & Invalid transactions

Q:

1. Is buying a land which is not identifiable like people buy for example 500 yards in a housing scheme but the plot purchased is not yet demarcated, permissible?

2. If one has such a land, is selling it and using that money to buy another land which is well identifieable permissible? (I mean using the money obtained by selling the land which was not identifiable permissible or not?

3. Buying a flat in installments in a building which is under construction, and hence the apartment one bought is not physically there when the agreement to purchase was signed. He then started to pay the installments, and his flat was, in the meanwhile constructed and he continued to pay. Is buying such a property which was not physically present permissible? Can one sell it once it is completed and he clears all the installments? Would the money obtained by selling it be halal?

Q: My friend has a business of selling stitched female clothes. I'm in another city and she made a deal with me and my sister that for every dress that I will struggle to get sold in my city, I'll be getting some profit ranging from 50 to 500 rupees, depending on what type of dress it is. So I call my female friends and relatives, and sometimes when I meet them, I tell them about the dresses, take their sizes and send them to my friend in the other city. She stitches the dresses and gives them to my sister who is also working with us. My sister then delivers the dress to my city. Is this income halal?

Q: Sometimes store owners ask us to help them out with stock that has not been sold and is sometimes past the sell by date.

1. Is it permissible to give them back the full value of the stock as a credit?

2. Is it permissible to swap the stock directly for a fresh lot?

Q: Ali sells tape to a shopkeeper. Can we also sell tape to the same shopkeeper by purchasing in bulk from Ali and sell to his same customer? 

Q: Some airlines, while making reservations, offer the option of paying additional charges to make a non-refundable and non-changeable ticket become a refundable and changeable ticket. Is this extra payment permissible?

Q: I am working in a company who has a price listed for items. I am in the sales department. Is it halal for me to buy products at a listed price from my own company and sell these products in the market at profit by not affecting the company's clients or sales volumes? Is getting profit for me in this way halal or not?

Q: Some stores give a card to frequent customers. They give items to card holders for lower prices than other people, and when the items are purchased, they get points which can be used in future to buy things for free from them. Is this allowed?

Q: Many businesses today engage in something called “round tripping”. What they do is purchase goods, thereafter they mark the goods for export and claim the vat back, while the actual goods are not exported but are instead sold locally.

From my understanding, in the process, there are lies spoken (lying to suppliers by saying that the goods are going over the border), bribes are given (a payment is made to border officials and revenue officials to stamp documents and release payments from the revenue services) and corruption is taking place. Is this practice allowed in Islam and is it permissible for us to purchase from these businesses?

Q: My husband is working in a private Afghan company that stores oil for America. Sometimes the Americans ask my husband for some goods like paint, furniture or other things. My husband asks the price from the shopkeeper and buys the goods then gives the goods with an increased price to the Americans.

For example, the furniture price is 300 dollars and my husband gives the price as 500 dollars, even the Americans know the real price but they accept the price that my husband gives.

I told my husband that this money is haram but he says that I am not their employee, I work for another company. They ask me to buy goods for them and I give them a quotation then they buy it. This is business. I don't directly tell them that I increased the price but they know. They accept it because they trust me and they need one person to do their work for them since they can't directly buy those things. I spend my time and effort for them in getting those things so the money is not haram. Kindly tell me whether the money my husband charges them is haram or halal. 

Q: Is it permissible for a person to purchase gold on credit?