Catch-22 is a situation where conflicting rules make the desired outcome impossible. It comes from a novel by the American author Joseph Heller, in which pilots would not have to fly missions if they were mentally ill, but not wanting to fly dangerous missions was held to be proof of sanity, so they had to fly anyway.
('Catch 22', without the hyphen, is also used.)
If a problem is 30, the problem is the person who sits 30 cm from the computer screen. It is used to describe people that lack technical knowledge and can be used when you insult someone who's having computer problems.
A speaker says "that makes two of us" to indicate agreement with what another speaker just said. For example, I can say, "I wish I would win the lottery." A listener who says "That makes two of us" is indicating the he or she wants to win the lottery, too.