Got some Poorboys SSR2 (after advice off here)

to give the old girl a decent shine for the coming year. How is it best to put on ? On with a buffer or by hand and off with a buffer ? I need to buy a buffer and i presume there are good ones and bad ones. Which ones do i avoid ? I presume there are different speed ones too, which speed would be best ? Also, i've been told to clay it but don't know what it is

Is this right and how is best to apply it ? Excuse my stupidity on this
cheeRS in advance