My S just finished his first semester in the Honors program. He took two classes and felt it was manageable. I’m not sure I would recommend taking courses like Physics or Math as Honors, but you certainly can take others. I don’t think there is a limit a my son was able to sign up for Honors classes at the NSC.
Honors classes are not necessary harder, but the classed tend to me smaller and more focused. If your are an engineering student, I recommend taking ENGR 111 and 112 as Honors. You’ll have a better chance of getting group members that will work hard.