Is there any add-apt-repository similar type command to add repository?
Debian base operating systems have add-apt-repository
command to add ppa repository. This is quite easy command. Is there any similar type of command in Fedora which can be used to add repository easily?
Repositories can be an rpm file so you can run dnf install as any other package, no special tool is needed.
And suppose I have installed that RPM using dnf install, then latter if the update for that RPM come, then does fedora install it when I run dnf update command?
Like any other rpm package if update of the package containing the repository information exists it will be updated when you do dnf update.