Is There A Way To Do An Auto Message Like "HIYA MY GOOD FREN!"
When Someone Starts A Coversation With You? Can I Change The Auto Message Too?

Personally, I think it would be easier for you to just set a quicktext up for this, so when someone starts up a conversation with you, you just type in /xhello (that's just an example) and when you press enter it will come up with "Hello, my good friend " or anything else you want to set it as.

To set this up go to:

Plus! > Preferences... > Conversations > Quick Text, once there press "Add", once there you put the shortcut that you want to use, and then in the box below type in what you would like to appear when you use this shortcut.

It should look like this:

ok thanks~~!