Streaming methods are your friend. Start with the follow method, and
email the API team about getting Shadow. If your use is legit (likely)
then they'll give you Shadow. If/when you outstrip Shadow they will
likely upgrade you then.
The only caveat to streaming is that if you miss some time
Slav,
You should use the shadow method in the Streaming API for this.
Contact a...@twitter.com to get access.
Also, there's already a Twitter to Facebook integration. You should
consider why you need to duplicate this already functional system. Any
API based approach isn't going to forward