Alastair, any options are available under settings in the app. I don't believe it's possible to change colours in the Android app. I can't speak for IOS.

Latitude & longitude are available to see on the website. I'm not aware of any way to do it on the app. 

For example:

When an address/street name is available CT tends to favour that. A simple workaround is to add a viapoint on the route that where you need the coordinates, click on it, in the text box select 'more' then choose 'Mapillary'. The coordinates will appear in the URL of the page that opens.