Hi All,
This is becoming a very interesting topic!
Here's a little more that I can add to it. First seat reservations are great, especially since they are free of charge with the JR Pass and you can do so at every JR station. I would absolutely recommend getting a reserved seat, even if your train will be departing soon. One reason is that you don't have to line up on the platform before the train arrives, in order to secure a non reserved seat (it's pure convenience). An other reason to make seat reservations, which is especially nice when you travel alone - is that reservations are made in such a way that you will often have two seats for your own (unless it is very busy of course), or you have guaranteed seating together.
The Narita Express is indeed reserved seats only, so when you make seat reservations for it, you may as well and reserve the Hikari at the same time :)
For train scedules and other route information I would certainly recommend using Hyperdia and comes with a couple of hidden features that will give you all the information you may want. Take this route for example. When you press Station timetable you get the full time table for all trains departing from that station on that day. When you press Train timetable you get the exact route information of the train and all stations and times where it will be stopping, in addition when you press Interval timetable you get an even more detailed time table.
As for station maps, it depends on the JR part that you are traveling with but JR East offers a great collection of English station maps which includes all the major station in Tokyo as well as Narita Airport, for Kyoto see our blog post here.
Enjoy!
Daniel