I have found using cruise on long journeys increases fuel consumption

Each bar on the fuel gauge roughly equates to 40mpg

You'll have to take the door card off and check the runners

Probably need lubricating

Refer to pages 77-78 of the manual as this explains the wiper INTERVAL speed including rain sensor settings if you have this I don't have it on-hand, I believe it is at my parents' house. Download it from here https://www.vauxhall.co.uk/owners/information-and-safety/owners-manuals/corsa.html

Strange once you recharged the battery everything was working but after a while the faults returned.

Could be either the battery is discharging or is not being charged properly.

I assume there is enough juice to start the car

Read the thread below

viewtopic.php?f=8&t=3829&p=28537&hilit=boot#p28537

averaging 39mg in my 1.4 n/a

Map updates are available but you have to pay for them

https://vauxhall.navigation.com/en_GB/VauxhallEMEA/GBP

If your car is brand new then you should have the latest version

Refer to pages 77-78 of the manual as this explains the wiper INTERVAL speed including rain sensor settings if you have this

This is nothing more than the car telling you it's needs servicing. Also oil is fine and doesn't need changing immediately so long as there is enough oil

As it's been almost 12 months since you had a service so you will start to get this message despite low mileage

Disconnect the battery for a start

Not sure if the airbag come with their own battery back up but wait 30 mins before attempting to take airbag off to avoid it deploying