Hi zingo79,
I don't know about chess clocks, but I can certainly recommend a book. I have Better Chess for Average Players by Tim Harding. If you're not looking for an in-depth coverage of all the topics you listed, then it might be what you're after. It covers forks, pins, skewers and zwischenzugs, combinations, pawn sacrifices, heavy sacrifices, exchange sacrifices, and a section on choosing a move, which is good, but it doesn't really touch on visualization. Each section runs between 6-9 pages, so you won't get loads of information on each subject. I find it's mostly "reminder" information-things you know but sometimes forget the specifics of.
Does anyone know of a cheap, but reliable, useful chess timer? Preferably from Amazon.
Does anyone know a great book for chess tactics, visualization, combination, sacrifices, and under $15? Please no beginner books, and again preferably from Amazon.
Sorry for the cheapness, I'm a teen.
Thanks, Zingo