The Czech currency is the Koruna, which means crown and is usually abbreviated to Kc. Each Koruna is divided into 100 haleru, although in Prague particularly you will rarely see anything smaller than a Koruna. As a rule of thumb the exchange rates as at December 2005 are as follows:
Notes and coins come in a wide variety of denominations, with quite large notes in popular use. This is worth bearing in mind when getting cash from a cash machine, as if you ask for 2000Kc they will happily issue a single 2000Kc note. 2000Kc will pay for rather a lot of stuff in the Czech Republic, and if you try and use this note to pay for anything costing less than about 200Kc you will be very unpopular indeed. It is a good idea to ask for slightly less than what you want - for example 1800Kc. The machine will then be forced to issue you with a range of smaller notes.
Public transport in the Czech republic is almost entirely run by the state, and is fairly well integrated. The best place to get information about times and fares for all modes of transport is IDOS - which runs an integrated public transport planning website for the country.
Stamps can be bought from Post Offices and various corner stores. Costs are probably the lowest in Europe - as at December 2005, costs for a standard letter up to 20g are:
Up to date prices, and full details are available from Ceska Posta
The Czech Republic has a large number of excellent hostels. Prague specializes in party hostels, where a cheap bar and crowds of backpackers and weekenders will ensure that you have better things to do than sleep for as long as you are there. There are however quieter more relaxed hostels where even in Prague you can have a quiet chat with some interesting characters and be fairly sure of a good night's sleep. Apart from one or two party hostels in tourist centres such as Brno and Cesky Krumlov, most hostels outside of Prague are of the more relaxed kind - places where you can spend a quiet week watching the world outside doing not-very-much, while you yourself do absolutely nothing but enjoy some beers and hopefully some like-minded company. Even the local Hostelling International affiliate (the czech Youth Hostelling Association seems to consist of a loose affiliation of relaxed well-run hostels, rather than the huge regimented institutions full of school parties you find in HI hostels elsewhere in Europe.
Most hostels in the Czech republic have some kind of kitchen which can be used to prepare food. Large supermarkets such as Tesco exist in most towns, and have a reasonable range of produce, though as this is not an expensive country it is usually perfectly reasonable to shop in any corner shop. A good selection of bread, meat, cheese, fish and dried goods such as pasta is available. Fruit and vegetables are fairly seasonal however, and in winter may be restricted to frozen spinach and pickled gherkins, with potatoes, onions and few very sorry-looking items such as green peppers lingering in the corner. This is fine for a while, but vegetarians in particular are likely to find they get quite bored after a week.
In the Czech Republic all eats are cheap eats! This is of course not quite true, and certainly doesn't apply in the centre of Prague, but in general you shouldn't need to look at the menus outside of more than one or two restaurants to find somewhere within your price range.
Most meals in Czech restaurants appear to be based around pork. This can be prepared in many different ways, but here it only seems to be in the form of sznitzel or cutlet. If you are feeling adventurous you could try trout, or take a vegetarian option, which will almost certainly be made from cheese. These will be served with some form of potato (brambory) or dumplings, and should you so desire you can order a side dish of vegetables. Occasionally there will be some kind of pasta option, and it is not impossible to find chicken and veal. If your dumplings have been covered with something suspiciously sweet then congratulations - you have discovered dessert! Most people will probably be quite happy with this for a few days, after which they will hanker for more international foods. Happily, anywhere that has any number of tourists will also have a selection of restaurants serving anyting from pizza to sushi.