Separate names with a comma.
No you need to click 'start a conversation' to to private chat.
I see no such option.
Not sure why. If you click my username in your introduction thread, you should see my profile page and the 'start a conversation' tag.
Don't click my username here. Click it in your introduction thread. I can't see the 'start a conversation' tag too if I click your name here.
When I click on your name in my intro thread, I see Billie48, Male from Canada. I see five light blue links to click on: Profile page, Follow, Ignore, Find All Posts and Find All Started Threads.
I am not sure if this is due to the newness of your username. You may want to ask others about this issue in the main support forum or better yet search out @Markku to ask him if there is a condition for starting a conversation.
Yes, thanks to @Contrast's clarification, new members can't do PM right away and that is why you don't see that option.