Hi. I am new here and I want to know more about debit card and how to use it.

I am currently studying in Singapore and I opened an OCBC Frank saving account here. And they issued me a mastercard debit card.

So my questions are as followed:-
1) Is it safe using debit card to purchase stuff online such as from groupon and air ticket?
2) Besides debit card number (the 16 digits in front), what other information is needed like PIN?
3) Is there a daily limit to my debit card? If there is, how do I check?
4) Are there any other stuff that I, a newbie to debit card usage, should know before I start utilizing it?
5) Is my debit card linked to my saving account in OCBC Frank?

Thanks for answering my questions although some may seem to be a stupid question.

This post has been edited by brandon114716: Jan 5 2013, 11:03 PM