You can also use "behave" when referring to the function of a machine or computer programme and how it works

As Chris says, "blue" often means sad or unhappy. For example "i'm feeling blue" or "I've got the blues" - means I'm feeling low, sad, unhappy. It could also be referring to a football team /supporter of a team that plays in blue (for example, in Liverpool there are two teams - Liverpool play in Red usually whereas Everton normally play in blue). Sounds more likely to be related to mood

"the" suggests something definite, "a" or "an" suggests multiple options. "The turn of the millennium" is correct. "a box of cereal" - there is more than one box of cereal. There is only one "turn of the millennium" (at least in a lifetime)

Oh and the correct spelling is "suggestions". Hope this helps :)

"To head to" is more definite - for example, we'll head to town later. "To head for" would be used on a road trip, for example "we'll head for London" (go towards) "on the way to the south coast"