display custom annotation per coordinate pulled from a locations.json file

We are working on an iOS-only travel app. The MapKit is a critical element of our design, and we have a few questions.

1. We want to add custom icons on specific points on the map, for example:

On 51.503301, -0.119564, add a custom icon of the London Eye

1. Annotating/highlighting an area on a map, for example:

Hydepark in London has a square, and we have 4 points on the map. We want to connect these points to form a square on the map with a custom colour.