Pogo Alert isn't a sat nav ... so there's no programming of destination.
Let's think about how GPS based camera alert devices work...
Because they don't know your destination (and hence which roads you are likely to be driving on) they have to make assumptions. The main assumption they make is that you will continue in the direction you are currently heading.
In your first example you will get warned about 1 of the 4 cameras IF it's straight over the roundabout, and you won't get warned about the other 3 cameras unless you turn onto one of those roads and then only when the device realises what your new heading is. In theory a camera very close to a roundabout could catch you unawares... which is why these devices are NOT infallible and why you still need to be watching and looking.
And in your second example, yes you will get warned about the camera on the exit you don't take. This happens to me every day - I approach a roundabout intending to turn left, but I get warned about the camera that is 200 yards further along the exit that is straight on. That's a false positive I can live with.
All the above is why adding camera alerts to the RNS-E is a great idea, provided you have an active route it knows which road you will probably be driving on and can warn you about cameras on turns and not warn you about cameras on exits which you probably won't be taking.
This is the current "plus point" of a mobile phone with GPS and running something like TomTom Navigator - it has route information AND camera location information (because applications like TomTom Navigator support the special POI type for cameras, and free databases are available to download).