Check the "IF NEW HERE" sticky thread at the top of the forum for an index of threads with lots of great information, including gearing info.
1/8 refers to the width of your gearing components. 1/8 is wider than 3/32, making 1/8 chains compatible with cogs and chainrings of both sizes.
Headsets are not universal, so you may have to do a bit of searching to figure out what's compatible with your frame. It might help to browse around PedalRoom for similar setups and build lists to see what headsets other riders are using.