Looking for best way to append something to a users signature + publish to facebook

[DetroitYES]

I want to build a vacation count down calendar that will display how many days remain until a user leaves. I'm confident in building the back end but not sure how to append it to the signature...

I was digging around showpost.php and showthread.php but it looks like the each post, its title, content, signature etc... is generated via a loop with no hooks...

I have to then imagine that the best solution is to write a plugin that queries for the date (if it exists and is in the future) around postbit_start and feed the data it into the postbit template?

I would also like to push this date out to the users facebook page every so often. Would it be wiser to utilize vbulletins built in facebook functionality and piggy back onto the existing app, or build my own standalone?

Thanks