There's a lot of interesting knowledge being dropped here re: Reggae, Calypso, Carnival/Carnavale, and socio-economic factors that not everyone considers. For those interested in an indepth study of Rastafarianism, Reggae, and social/class issues, I'd suggest Barry Chevannes book "Rastafari: Roots & Ideology" as a good start. For the Hip-Hop heads, you might be interested in looking at one of the roots of rap-- Trinadadian Extempo (improvised rhyming song lyrical tradition).
Short answers to the OP's initial question(s)-- yes, it's timabales (traditionally a Latin instrument), not steel drums that you hear in Marley's and others roots reggae work. And yes, the steel drums (or more properly, pans) were invented in Trinidad, but are also used in Jamaica (but not indigenous to).
Percussion instruments in roots reggae? Drumset, of course, timbales (played in a variety of ways, from the traditional, to the unique-- check out Bunny Wailer's brush playing on some of the original Wailers tunes and live performances), congas, bongos, and djembe; but also you hear a lot of vibra-slap/quijada, triangle, shakers, tambourine, woodblocks, cowbells, and ago-go bells.
One of the guys who "wrote the book," so to speak, on hand percussion/"toys" in Jamaican roots reggae was Alvin "Seeco" Patterson. He always played the right instrument, and the right rhythm, at the right time. Check out some of his amazing triangle work on the Wailer's sides. A lot of these guys, including Seeco, were not virtuosos in the way that some of the Latin, Brazilian, and African hand drummers and percussionists have been, but their creativity and ability to know exactly what's right for the song always amazes me.
Simple, elegant, and perfect grooves. Kind of like, if Ringo Starr was an indigenous Jamaican guy that played reggae-- basic, to the point, and perfectly placed for maximum effect.
GJ