...Unless it's a quote. :)
I wouldn't call this a mistake. When you're first writing your draft, you're trying to get the ideas down, not polish it up. When you first...
Neither. That's what exclamation points are for. And use them sparingly.
Hello, all... I've been writing for years, more so this last year or two than the rest. So much so that I have a novel about 90% finished....
Separate names with a comma.