What you called is a third party that handles only a very limited amount of things for avast for free.
And yes, it is including configuration.
If you know the name of that person, please mention it here.
1]
https://www.avast.com/faq.php?article=AVKB1772]
Why do you think you are missing something ?
avast has that option for a long time as do several other av's
https://www.avast.com/faq.php?article=AVKB1143]
It should be there if you right click a file/folder.
If not there is something wrong with your installation.
Perform a repair of avast and see if the problem is solved.
Before doing so, make sure any previous installed av is completely removed.
4]
Yes you can see what is detected and no you can not resolve everything as some things need a paid subscription for other software from avast.
5]
Secureline is not free.
It can be there is a trial installed
Also what are the differences between Premier & Internet Security?
Why not look at the avast website ?
https://www.avast.com/compare-antivirushttps://www.avast.com/faq.php