I am thinking that my ale would taste great with it. Tastes fine as is but I think I think I was supposed to dry hop instead of just adding the hops in at last then strain. So it needs more flavor
Do you mean adding it to the glass of beer after you pour it out of the carb'd bottle?
Shouldn't be a problem. http://www.homebrewit.com/aisle/p/3510
This link says you can add the bottle of flavoring anytime in the keg, up to serving.
Do I have to shake it?
to quote the info in the link above..... "stir well, but gently"
I have blueberry extract on hand that is about a year old.. Is that safe to use? I used 2ozs quite some time ago.
At 4 bucks for a bottle of 4 oz's. I would buy a new bottle and add it all to the keg.