Not necessarily. Static IP and PTR records improve the "credibility" factor, but it's not required. I'm running mine on the dynamic IP provided by the ISP, without PTR. Despite the warnings I get from the mail scanning tools, I can send mail to Gmail, Yahoo and the other major providers.
Not if you are on hetzner or one of the other major spam hosting ISP ranges. You will blocked in a lot of places.
Folks talk about these places and the "unlimited" bandwidth and the "friendly" abuse teams. Ergo - you can't talk to as many other places via email. The big players will crunch you down quick.
