vaccuum leak?

ok sorry i forgot to say the pics are of a couple of holes, and im wondering if they are what could be causing a vaccuum leak. sorry for confusion. the first pic is of a threaded hole in the intake and im not sure if there is supposed to be a bolt in there.
the second and third is of a "valley" on the carb, but im not sure if it goes through, it doesnt feel like it.
and the fourth is of a small hole on the bottom that isnt threaded or anything but im not sure what it is for.

and ill be sure to give it a good cleaning too ;)