Overwhelmed at trying to book all seats/tickets for trains before I leave because I will be in Italy 2nd two weeks in August (Holiday for the locals) ... who has been to Cinque Terre, Tuscany, & Rome at this time? Can I book a day or two ahead at the train station or will I never get a seat?
Don't worry. It's easy to buy tickets at the train station. If you want peace of mind, you can stop by the station the day or two before to buy tickets, but it's not necessary.
Not to worry, it sounds a lot harder than it is. Let the machine in the train station worry about whether a route is the IC, Eurostar, etc; just call up the schedule in English and pick the times that are convenient for you. Some have said that more popular trains may fill day of travel so that's one reason to book a day or two ahead. I never experienced that personally, but I was there in Sept. My reason for getting tix a day or two ahead is so you don't waste time in train stations waiting for a train; your time is limited and valuable, spending 2-3 hours a few times cooling your heels costs you almost a day of your vacation!
Getting a ticket and getting a reservation (seat) are two different things. At busy times or on popular routes it is safest to have a reservation for a specific seat on a specific train. Some trains get so crowded that people are left standing, especially in 2nd class. I buy my reservations a day or two in advance when I can; I'm usually traveling with a RailPass. If you have no RailPass, you can buy the ticket before or at the same time you buy the reservation. Be sure to time/date your ticket at the yellow box before boarding the train.