if you don't pay the bill by the due date, 7 days later Aydem issue a disconnection notice & that gives you a further 3 days to pay. After that, yes, the electricity will be cut off. Once it's paid, it's usually only be a matter of an hour or so before the man comes round & reconnects.
To get a tax no you'll have to visit the tax office, taking with you a photocopy of your passport.
Once you have a bank account, all that's needed to set up DDs are copies of your recent bills, but please note that not all the banks will do a DD for water.