Where can one look up the actual legal definition for any given word?
Legislation often includes a section dedicated to definitions, commonly the first or last clause in a subsection of the US code. The holdings of court cases are also a significant source of information (but you have to distinguish between the holding, which is highly technical and narrow, and the dicta which is the long and often wide-ranging explanations of what the holding means that makes up the bulk of a judicial opinion, but which do not themselves have the force of law).
Have you heard the claim that your name in all caps is different than your name as you would write it? What is your opinion on that claim?
Complete garbage. I don't want to spend time or energy digging up all the references for you, but you can safely assume that anyone advancing that argument is a crazy trying to get out of paying income taxes (similar arguments include claims that having a certain kind of flag in the courtroom nullifies the legal force of a judicial decision and that your social security card is actually a certificate of slavery). Almost all such arguments originate from a set of fringe Christian conspiracy theories informally known as Dominionism in which (among other things) the federal government is considered an invention of Satan designed to trick Christians out of their rightful place as rulers over the Promised Land. See https://en.wikipedia.org/wiki/Christian_Reconstructionism
Surprising or counter-intuititve legal arguments that lean heavily on 'natural law' often turn out to be grounded in religious belief as well.
IANAL but it's highly dependent on context, and in many cases it's a matter of simply being extremely precise. For example, if I say "I'm not reading your email" note that I didn't say, for instance, that I'm not _collecting_ your email. Also, I didn't say I won't read it later. I also never said nobody else is reading your email right now.
It is interesting to compare this to a different thread about fallacies. If you're seeking the truth it's good to interpret someone's statements charitably. However when somebody in government says something, it's better to interpret it as cynically as possible, because that's where the unconstrained power forms.
"Where can one look up the actual legal definition for any given word?"
Words don't have universal legal definitions. However, at the start of a law there is usually a list of terms and how they are defined for the purposes of that law. So if want to know whether or not you can be prosecuted for X, you need to look up how the relevant terms are defined in the laws for X.
In the case of emails and phone records, in many cases the NSA isn't intercepting that information. Rather, the ISPs/telcos are intercepting it and sending the data to the NSA.
And many times the terms are defined as a reference to another part of the law. I'm not sure if there is ever a chain of references ("...as defined in secA, secA says: see secB, etc..."), but I wouldn't be surprised.
I believe it is required for some sections to be in all-caps in regards to EULAs to make it more obvious it is there. Specifically, disclaimers, waivers of liability and warranties are almost always in capitol letters.
Have you heard the claim that your name in all caps is different than your name as you would write it? What is your opinion on that claim?