It all really depends on your expectations.
As for sewing itself, a sewing machine is great - though you can do it all by hand.
Really all you need is machine, thread, scissors, material. You'd need a hand-sewing needle for things like buttons, and it might be easier to have a seam ripper (though I usually end up using scissors anyway). You might want a thimble if you will end up hand-sewing.
You can buy a pattern and alter it or make your own. Since it's your first project, buying one might be the way to go, but it depends on your experience and what you're good at. There are lots of "pirate coat" patterns so you in luck in that regard - you can pick one out and modify it pretty easily.
Since this is your first project, I'd recommend using something like a bottomweight cotton twill (I'd use a heavy wool melton as an ideal - but I think you'd prefer to not spend $20+/y on fabric for your first project!). Remember to buy cheap $1/y muslin fabric to make a "test" first. That way you can get a feel for sewing without risking your more expensive fabric. At first you might want to take fabric and practice sewing straight and curved lines and such - get familiar with the machine if you are using one.
Having a pattern will walk you through most of it so it will tell you how much interfacing you need and what kind. This won't give perfect results, but it's up to you what your expectations are. This is a reasonable first project, I think - and it might be best to keep it simple.