Scans

bitdefender total security's scan rules are not defined in detail , not in the app neither on the website. i hope u may provide the answer.
1- Does a System Scan contain root kit/bios/ all file's scans , regardless of new/old ?
2- The rescue environment does not scan for the types above , why ? and why system & the rescue scans can not be configured by the user as it provides more free hand to the user.
3- There should be a cheaper plan for it's Total security e.g. for 1/2/3 users as do not & hopefully ll not ve 😀more than 3 devices.
Thx v much for your precious time & special care.
best regards