Is it true that Google and other search engines will ignore part of your page titles if they're over 68 characters long and your meta content if its too long?
Yes, they will only read a certain amount of charcters and in search results strip off what exceeds the maximum.
The above is correct, that said, going over the limit is not always a bad thing. Don't go over by loads of word, just one or two because one you have broken the accepted limit you'll see .... at the end of the allowed characters in the search results. The good thing about that is, if you write your description well and compelling, just at the point where it "cuts off". This will make the visitor want to click through and see what the rest of the words are. So it can increase CTR. I never stick to the allowed limits. KP
From what I have read most agree that this is true and they will point out if your meta tags are to short as well.
the shorter the better remember that google knows if your just stuffing keywords this can hit your site badly