Conveying the message of Islam to people living on an isolated island

Q: I read that there’s an isolated island off the coast of India, the sentinel islands. A tribe of people dwell on this island and have been isolated from the rest of society for centuries. They are unaware of the cultures, religions and technologies that exist throughout the rest of the world. This group of people and their way of life are protected due to the fact that they haven’t been exposed to half the viruses and diseases that exist on the mainlands. How will this group of people be judged?

Designing a structure for a church and selling grapes to someone who will use it to make wine

Q:

1. Is it permissible for an engineer to design the structure (i.e. steel in beams, columns, etc.) of a building which the owners will use for producing alcohol?

2. Is it permissible for an engineer to design the structure of a church?

3. Is it permissible to sell grapes to someone who will use it for making wine?

Returning an item that does not belong to you

Q: When I was a child I remember one of the neighbours close to us had a garden that from what I remember was quite messy like things were about and one thing there was a tricycle and it looked like the one I had when I was a child and to think at the time I thought someone must have dumped my tricycle there so I took it out.

However I cannot ascertain if it did belong to me and perhaps I took someone’s tricycle, maybe I thought the garden was messy so my tricycle was dumped there.

I believe the family have moved out now and there are new owners of the house. Would I have to approach the current owners to see if they are in contact with the old owners so I can ask the old owners for forgiveness and pay them if that is required of me.