For the first question, one has to bear in mind that texts and pictures for web viewing don't occupy that much space - besides on the more massindustrial level.
Visitors also don't just all come at once - having that bandwidth available costs money, you might not need as much as you think. If you just want to tinker around, perhaps a simple webhotel, space through your ISP or a small server might do it?
Streaming puts other restrictions and possibilities into the game - the hosting service needs to have a streaming server like IceCast running or let you install yours (might be difficult to find). Of course there's a legal issue too...
I have no idea about specific hosting services! Perhaps we have some knowledgeable people running around here?
For your own server, I'd recommend Linux. FreeBSD is very good too, but slightly more complicated. You can however setup a server in Windows for free, see for instance
www.apache.org.
If you're going to put up your own server, you'll want a secure system and a system that you can control satisfactorily. To save some money and hone your skills, you might want to install a Linux system on your desktop, either beside or on top of your existing OS. I personally like Ubuntu Linux, which is derived from Debian, probably the most stable and secure distribution. The difference is that Ubuntu works out of the box with a graphical user interface, Debian puts you straight at the command line.They are both free and there are many other choises. Debian also has a mind nuggingly slow release schedule, which may or may not be a problem since backports of security patches are made ASAP.
It is not necessary to learn all command line stuff in Ubuntu, but the beauty is that it lets you be however point and clicky or under-the-hood as you like. Of course, to lap security holes with precision and put in certain countermeasures requires you to have a bit of knowledge and touch the command line.
There's endless to be said on this...