Yes it is, however, you can keep it as long as you like. It never expires....I had mine for over 2 years back in May when I had to use it, and I've since bought another and have yet to use it.

Yes.

=( sad but happy about this=)

yep and you can have it equipped forever if you never missed a day but as soon as you miss a day you have to equip it again so keep in mind you can't miss more than a day

I think so

A streak freeze is always equipped there if you buy it unless you miss a day and it will be used. you don't have to use it the day you buy it, you can just store it there just in case. I recommend buying one just in case.