My Haynes manuals usually include a page with color photos to compare your spark plugs to. It will also give you causes and symptoms that the old spark plugs can tell you about each cylinder, ideally you would want every spark plug to look the same with a brown to grayish tan color. I say ideally, because we are talking about a 20 year old truck with a fair amount of miles on it.
Yes, the throttle body can be cleaned. It seems pretty intimidating at first, but it's not really as bad as it seems. It's a good idea to get a set of line wrenches and be careful not to mess up the hard fuel lines. It's a good time to put a gasket set into it as well. I got one from advanced auto from BWD( I think it cost about $45) that included the diaphragm for the fuel pressure regulator as well. Mine took me about 3 hours an several cans of throttle body cleaner. Just take your time, study the diagram and the instructions before you start and you will be fine... I was amazed at how much crud and gunk was built up into all the little passages, I had a noticable improvement after cleaning and rebuilding mine, but mine was pretty gummed up.