[squidsk]

1. Attachments are always inserted at the bottom. You can't insert them part way through the post.

2. There's a plugin that enables it, search vb3 mods for private message attachment

3. That' the behaviour you're supposed to see, when you quote a post you quote the entire post, if you want only part of it delete the bits you don't want.

4. There's some hardcoded stuff you'd need to change in order to be able to have nested quotes when quoting another post that itself quotes other posts.