Hey guys,
I'm building a treble booster ala Brian may as my first pedal and I'm about to order the parts online from an electronics supplier.

I'm looking at, for example, 100k resistors and some of them say1w, 1/2w 1%, 1/4 5%, 1/4w 1%. The diagram I'm following doesn't state the watt and percentages. When it comes to those things and building a pedal, do I need to order something specific if it's not stated? I think I read somewhere that un general when building pedals 1/4 is mainly used. But I wanna be sure.

The diagram I'm following (http://www.paulinthelab.com/2013/03/greg-fryer-brian-may-treble-booster.html)

Also, what is that item part/plugin called that allows you to use a power supply instead of a battery?

Thanks guys!
Long Live Rock n' Roll
1/4W is fine. Pedals almost never approach that amount of power, so if it doesn't specify then you don't need to worry about it. Some people even use 1/8W as standard with no issues.

The power supply receptacle is usually called a barrel jack. The standard one is 2.1mm, center negative.