Cinque Terre to Paris

Kate, As it's your first trip abroad, I'd normally recommend reading Europe Through The Back Door prior to your trip, but realize it may not be available in Oz. It provides a lot of good information on "how" to travel well in Europe. If available in your area, the country-specific Guidebooks have good information on hotels, restaurants, transportation, sightseeing, etc. Many of these are also available as E-books, which you may be able to download. It's very easy to get from Rome to the Cinque Terre. You can research the rail trips using the Trenitalia website. The easiest trip will be one of the direct trains (no changes) from Roma Termini to La Spezia Centrale. I'd use the departure at 09:40, arriving 13:46 (time 4H:06M, reservations compulsory). At La Spezia, you'll transfer to the local trains for the trip to whichever of the five towns you'll be staying in. When is this trip taking place? I would highly recommend pre-booking accommodations in the C.T. WELL in advance. Have you looked at lodgings there yet? Regarding travel to Paris, you could travel by train but it's a long trip, even if you stop for a night or two at an intermediate location. The easiest and cheapest method would be to take an EasyJet flight from Pisa to Paris (flight time 1H:40M). You could possibly split your extra days by adding a day in the C.T. and a day in Paris. Travel time from La Spezia to Pisa Airport is ~1.5H (one change at Pisa Centrale). Happy travels!

Kate, As it's your first trip to Italy, some "caveats" regarding rail travel.... When travelling on Regionale trains which don't require reservations, it's ESSENTIAL to validate (time & date stamp) the tickets prior to boarding the train on the day of travel.  This includes the Leonardo Express which travels from the airport to Roma Termini.  The validation (Convalida) machine will either be bright yellow or blue & gray, with a small digital display on the front.  These are easy to find and located near the tracks.  If the machine is not working, writing the time & date on the ticket may be acceptable (ask the Conductor as soon as possible).  Those caught with unvalidated tickets may be fined on the spot! If using the small tickets, these are in-serted on the left side of the validation machines. The fines start at €50 per person and if not paid on the spot, these DOUBLE and increase from there!  The same fines apply to those travelling via Bus in Rome and other places (in that case, validation machines are often located on-board the Bus).  Conductors are now carrying portable debit/credit card Terminals, so payment of fines will be easily accomplished! Those travelling on the "premium" trains such as the Freccia (high speed) trains MUST have a valid reservation or again may be fined on the spot! These fines also start at €50 per person, plus the cost of the reservation, which is currently ~€10.  Reservations are compulsory and are specific to a particular train and departure time. It's NOT POSSIBLE to simply buy a ticket with reservations and then board any train.  The ticket or reservation will specify the train number (ie: ES-9718), so it's important to verify that before boarding.

Amazingly helpful advice Ken! Cannot tell you how appreciative I am. Would it be worth it do you think to spend time in Pisa? At this stage my options are 3 nights in Cinque Terre, 3 nights in Paris, and two nights somewhere in between...OR...I do as you said and spend the additional time in either Cinque Terre or Paris (or both). As exciting as it is, it's also quite daunting! Determined however to plan it myself rather than rely on a travel agent.
Thank you again...

I would spend the extra time in Paris. There is so much to see you won't even scratch the surface. Pisa is worth an hour IF you don't have to go out of your way for it. If the train from Rome to CT stops in Pisa you could get off, stash your bag at the luggage storage at the train station and head over to the Field of Miracles. If the train doesn't stop there you really haven't missed much.