Probably the first thing you should do upon arriving in Liege is get a bank account. A passport is enough to open the account, you do not need to be a legal resident yet. You should however update with your Id card as soon as you can. Some banks will deal with you immediately, others give you an appointment in the next few days (in some cases even make the appointment on line).
Certain banks have accounts which do not charge fees (20-50 euros / year), in particular ING, but also DeutscheBank, Beobank (new). There are 2 agencies near university – Fortis and Belfius, but I would not recommend either – the accounts are not particularly advantageous. Much more choice down town.
As soon as possible, get a credit card too, for conferences etc… In most instances you have to pay in advance and get reimbursed by the university. A fake credit card which you can recharge is not a real substitute if you need a guarantee for a rental car or something like that.
To take out cash you can go to any bank, but will probably pay 10 cents or so, unless it is your own bank. Many shops have the Belgian debit card network “Bancontact”. Whichever your bank you can use that. Most will take credit cards too. Restaurants only take credit (almost never Bancontact) and some only take cash. To use your card abroad you have to go activate it at your bank (by default they block usage outside Belgium).
NB: some sites ask for the Belgian bank account number, which is just the last 12 digits of the IBAN number (chop off the BExx in the front).