Welcome to mp3car. First the link for the amplifier isn't working right. Every time I click on it it just takes me to ebays home page. Second, I would recommend NOT buying from ebay. You could probably get better prices someplace else and with ebay there's no telling what kind of condition a product may actually be in.
Anyways, because I can't see the amp I can't tell you if It can connect using optical but 99.99% of the time, your amp is gonna get it's source from either RCA's or high level inputs only. If you want to go from optical to RCA then the most common thing needed is a sound processor with optical inputs but they become pretty pricey. Usually the same cost as a decent computer it's self.
Just to get you going, the sub and amp will be probably be a good starting point. But if your like me and hate listening to people drive down the road with music blasting but all you can hear is their car rattling then I would recommend lining pretty much the whole car with vibration dampener. There are many different brands that of vibration dampeners such as Dynamat, Damplifier Pro, and Audio Technix, just to name a few. I like to line the whole car, even under the dash. Be aware though. Most vibration dampeners are a bit heavy and some may smell bad or not stick well so look out for the bad stuff. Do research on everything. Read reviews. There's a vast amount of information on here.
Now regarding door speakers. That is up to you mainly. You could run two way or more coaxials in you doors or you can run components with a tweeter in your a pillars or wherever else you may decide to mount them. You can run them directly off of a head units amp if your using one or you could use external amps for more power if you like.
Then the biggest thing in car audio is power. Remember that you really cant get TOO BIG with your your power cables. I'd recommend grounding your amps to the chassis of your car, keep your ground cable as short as possible, keep it the same diameter as your power cable and try to minimize grounding point in the car (ground two or more amps on one bolt. It will help with ground loops). For the size of wire you should use is more or less up to you. If your running small low power amps then the variety of cable sizes and lengths are large. I'f you're running high power amps then the variety gets slimmer. If you need some references on the smallest cables you should use then you should do some research on charts. "the12volt.com" has some pretty good charts here.
Good luck. And if you don't mind, I'm sure all of us would like to see a worklog.