no, assumptions seldom prove true here.
every utility is different, but most will only send you a copy of your paper bill if you ask each time.
Paying online is complicated- there are at least 3 different ways to pay online- with a credit card from a paper bill, from a bank account each time, or, the mythical "debito automatico", where its automatically debited from your bank account each month.
But every utility, again, is different, some will only do one or another of these, some will take both LINK and Banelco, some only one or the other.
If you have a local bank account, you can pay some from it- theoretically, but sometimes its easier than other times. Expect 2, or 3, different codigos and claves, expect that some will only let you pay online if you have the number of the factura, and on and on.
Its possible, but not easy.
A great example of this is the RapiPago link Igor posted- it takes you to ONE, entirely static page, which does not, in fact allow you to pay anything online- instead, it tells you the phone number you must call...
