There are quite a few introduction to Garmin Edge computers on YouTube, showing their functionality. some are from Garmin others are by individuals giving demos. I think they would help answer your questions. I use an Edge 530 and have for about 4 years. I will be getting the bigger screen 1040 soon to help see the maps more clearly.
Garmins are on sale right now until June 16th. up to 20% on the more advanced models. the entry levels models are not on sale. This is a rare event. Garmin has a price fix at all vendors.

a video example: