Is it true that if we make big mosques with expensive things then we get more reward rather than makin simple mosques.

1: Is it true that if we make big mosques with expensive things then we get more reward rather than makin simple mosques. For example if we make the entire mosque with expensive marble, gold plated ceiling and taps in washroom. the most expensive carpets in the world and also the most expensive decorating in the world so we get more sawab (reward) when compared to making simple mosques of concrete and stones. ? Allah says that people in heaven will get big gold castles. So inshahAllah if Allah gives me alot of money and I make mosques like mentioned above so is there more sawab or same as making a simple mosque.?

2: Allah says in Surah Muzammil (I think im right) that "keep giving Allah Qaraz-a-e-Hasna" what does this aayah mean ? How can we give qarza (loan)-e-hasna to Allah and how will Allah reward us back ?

3. People say that everything about to happen in our lives is already written so leave it to fate and God. But Allah says that "Dua" can change the life and fate of a person. Allah says "Pray to me and i will answer" Please explain this issue.