Think in my normally bumbling fashion, i'm now going to contradict bits of what everybody else has said....
1. Eurostar is a passenger only train and serves:
In England
- London Waterloo
- Ashford International (in Kent - pick up towards Europe and set down towards London only i.e. you can't travel London to Ashford or vv)
- Eurostar doesn't stop in Folkestone
In France
- Calais Frethun (not many trains and the station is in the middle of a field about 10km from Calais)
- Lille Europe (good TGV connections to most of France)
- Paris Nord
- In addition, there is a daily service from London/Ashford to Marne La Valley Chessy (for Eurodisney) plus 1 summer Saturdays return to Avignon, and 2 weekly winter returns to the French Alps.
In Belgium
- Brussel/Bruxelles Zuid-Midi
2. Cars abroad - No problem at all. Some rental companies allow cars to be taken from Eng-Fra or vv, but that depends upon the company rules/insurance etc. As Becky says, you will need to carry different things in different countries (i.e bulb sets/hazard warning etc) and cars from both countries are supposed to have stickers placed on the lights to divert them (so that the dipped headlights dip to the side of the road, and not into the face of oncoming drivers). Also, things like legal driving age and blood- alcohol levels are different.
3. Le shuttle - Is for vehicles only (i.e. no foot passenges) and runs shuttles between Cheriton (near Folkestone) and Coquelle (near Calais). There are both car and freight shuttles running frequently 24hours a day.
To slightly contradict Sam, there is a Motorrail service in the UK (London - Penzance, but i think summer only), bt the rest was killed off by the Tories. There is a rumour of restarting a London-Scotland service this summer, but this has been going for a couple of years and i wouldn't hold your breath.
There are a number of services in Western Europe, but unfortunately in the past 2 or 3 years, many of these have been cut / replaced / diverted / scaled back as well.