1. The SDK lists all the events that occur when creating, publishing, deleting, or moving content. http://world.episerver.com/Documentation/Class-library/?documentId=cms/7/b0f80af7-479f-2fce-5efb-f7d5cdc2c8d7
2. PendingPublish is used when a piece of content is marked as "Ready for Publish" by the editor. It has been saved/checked in, but is not yet published.
3. In most cases that assummption is correct, but you can separate the public facing part of EPiServer from the editor-facing part by setting your site up on two servers (one in DMZ, one behind your firewall) and configuring no editor access on the public one. They need to share the same database and VPP (file archive) though.
4. See above
I'm new to EPiServer and have questions related to publishing content. In case my terminology is not yet correct, by "content" I mean pages and blocks.
Thank you very much,