Moreover, I found that
(1 to 2) != 10 returns false, and (1,2) != 10 returns true.... I am really missing something here, this must be a faq somewhere :S ).

Well, I'm missing something too because (1 to 2) and (1,2) are the same
sequence.

So

(1 to 2) != 10

means

some $x in (1 to 2) satisfies $x ne 10

which of course is true.