1. they will only text you if there is a problem with the result.
2. u cant see the result. they automatically upload it to the concerned databases.
3. you can go to extend the visa after 3-4 working after the test is done (suggested to go after 5-7 working days if u have time).
4. yes, you can extend it for 5 months in one shot. you dont need to go every month to renew.