Always glad to hear from you Allison.
The rock and roll piano sound from Jerry Lee was very influenced by late 1930`s boogie woogie piano played by guys like Cow Cow Davenport,Albert Ammons,Meude Lux Lewis,etc. so Jerry Lee revived that stuff 20 years after the fact and called rock and roll piano,hardly.
I`m glad to hear your friends band did a Slim Harpo tune,that`s cool Slim is very forgotten in my opinion,glad someone does his tunes,the stones love him,like on exile when they do "Shake your hips".
Jazz is`nt easy to get into,it usually takes more brain power from me than rock music but it is worth the effort,check out some Miles Davis like Kind Of Blue or John Coltrane`s Giant Steps for starters or the radio,though I find there`s too much recent jazz stuff instead of the old classics,that bothers me because that is what people should know,not any of the stuff around today,just rehashing the past,listen to the past!that`s the best stuff!