sup gaiz. want to ask advice on general life (again).

looking into getting a credit card. want to use it as security incase i run across an unexpected bill that i don't have cash-on-hand for, want to use it to increase my credit history, and want to use it to get heaps of frequent flyer points.

need to just get some clarification, that the internet isn't really spelling out for me.

looking into this kind of card: http://www.americanexpress.com/austr...CPID=100036881

amex qantas discovery card. no annual card fee, frequent flyer points for every dollar spent, etc. up to 44days interest free.

so just say i use this for every purchase i make from hereonin. if i keep on top of what i spent, when, and paid the card off in full by the due date, will the credit card cost me absolutely nothing? if i stay on top of it organisation-wise, will it be just like paying for it with my bank account but i get the added advantages of gaining a good credit history, getting points, etc?

when/where does the idea of getting a credit card turn bad? is it just if i don't pay by the right time, and interest/debt fxxxs me over?

cheers to everyone of all sized ears