I'm only going to answer the "getting round London" bit of your question.

Buy an A-Z. This is a small book of maps with every street in London and most of the main sites indexed at the rear. It shows the Tube stops.

Buy the most financially efficient London Transport pass (no idea what it is, sorry)- they let you travle on the ube and the buses. Personally I've never masterd the bus sytem in Lonodn, but the Tube is easy peasy lemon squeezy.

Fodors will not thank me for saying this, but they are upmarket. For students on a budget, get something more "you" by way of a guide- the Rough Guide,Lonely Travel or Let's Go.

And when you get to London buy a copy of Time Out magazine.

Also, ASK. People will help you.

Chill and have a great time.

If you give the name or address of the places you are staying, people here will give you good enough descriptions of how to get there.

Does www.multimap.co.uk help for your London accommodation? As Sheila says, I would buy a small A-Z covering central London if your guidebooks don't have detailed maps, this will help you get around. Lots of places are signposted once you get to the nearest tube stop so you won't have too much trouble finding places.

You can easily but the train tickets from Rome to Florence and back after you get to Italy. You can buy them ahead of time either at a railroad station or you can get them at any local travel agency. Unless the Trenitali website is offering some sort of sale on seats there should be no other reason to buy ahead of time.

I assume you will not be taking Eurostar trains (the tickets for which, include the seat reservation) so whether or not you want, or need a seat reservation (which usually only costs a couple of Euros for regular trains) might come up.

My advice: if you really want to save every penny then plan on getting one of the trains that originates in Rome. Get to the designated platform early; be one of the first to board the train as there will almost undoubtedly be unreserved seats available; look for those.

If you know the addresses and you just want to place them on a map, then use:
www.mappy.com
You can also enter two addresses and getting walking routes and distances (use 'pedestrian' option).

The local tourist offices in each city will surely have maps that place all the major sights on them...even look in the McDonalds, I know they used to have maps in Rome.

Ask your hotel desk clerk where the nearest grocer is, and then you can buy 'picnic' food for some of your meals.

Hi Foo,

You can buy your tickets Rome/Florence online (you get an instant confirmation)at www.trenitalia.com.

If you are flying into Rome FCO you can buy them at the FCO train station when you buy your tickets to Roma TE.

You can buy them at Roma TE upon arrival.

>Aside from it being the slowest, I don't see any problems with riding the regular train, as opposed to the nicer trains.<

Sometimes the IC trains take only a few minutes more than the ES*. The major difference is that ES* trains run on time. Keep in mind that you are in Italy and don't get upset if your IC shows up 3/4 hr late and arrives 2 hr late.

>...how to get to the major sites.<

www.mappy.com allows you to enter two addresses and find the pedestrian route. Change "express" to "pedestrian".

>If I need to ship purchased items, would mailing them home be a good idea?<
Yes.

>Is there some sort of locker at an airport or train terminal ...<

You can find the location of the left luggage office at Roma TE at http://www.romatermini.it/indexf.cfm