reflector and config are the only flag that are not appended to pacman (or yay)
instead reflector resolves to reflector with the previously used parameters stored in /etc/pacman.d/mirrorlist
and config resolves to nano /etc/pacman.conf.

sudo gets prepended automatically if the command requires root privileges, if the UID is not 0 (you are not root) and if sudo installed.
no, there is no check if your user is in the sudo group, if you download this script you should already be, or know you can only use part of this utility
tho such a feature is planned, to make the script truly ubiquitus.