Is it ok to drive slow on a freeway inthe right lane? and question about slow lights?

if the speed limit is 55-65 how slow can i drive in that lane or is it safer to drive in the middle of the lane at the posted speed limit like if i went 60 instead of 65. and if i slow down if somebody passes me and take my foot off the gas does that trigger the slow signal? i'm still learning to drive got my permit soon i wll get licence.