Move to help :)
Not entirely sure how old this doc is but here is most of the Material types https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/Material.html
if(blockType == Material.Whatever
Yes HashMaps are the way to go. I have used it in SideKick for various parts of the Mini Game Side as well as SideKicks economy.
Separate names with a comma.