Q1: [FIRST NAME GOES HERE] is how the first name personalization code will display in preview emails :) If you're seeing that, it means you added the code correctly! In the 'actual' send (i.e. not a preview), it'll populate the first name there. The only way to test it that way would be to actually send the broadcast to yourself — we have a guide on that here3.
Q2: It sounds like you might be our using our Text Only template, which is quite plain in terms of styling. I'd recommend creating a new template and adding whatever styling you'd like. We have a guide on our visual template editor here: The Visual Email Template Editor3 — Once your new template is created, you can select it as your default from the templates page in your account (linked above), by clicking the 'Use this template' button that will show up underneath it. Your account's incentive emails will use your account's default template!
Q3: Unfortunately I don't think there's a way to add line breaks in the title of a community post! :( Sorry about that.