IIR filter and phase shift
I believe you have received no answers to your questions because your first three questions are so strange, so puzzling, that no one where to start to even begin to compose answers.  See:

http://www.bing.com/videos/search?q=digital%20filter%20phase%20response&amp;qs=n&amp;form=QBVR&amp;pq=digital%20filter%20phase%20response&amp;sc=0-0&amp;sp=-1&amp;sk=#view=detail&amp;mid=3DC56A834B9C701B5FE93DC56A834B9C701B5FE9

and

http://www.bing.com/videos/search?q=digital%20filter%20phase%20response&amp;qs=n&amp;form=QBVR&amp;pq=digital%20filter%20phase%20response&amp;sc=0-0&amp;sp=-1&amp;sk=#view=detail&amp;mid=85921946745DEDD05D7385921946745DEDD05D73

Good Luck.