To manually pay at your own convenience, I use crysta. That's an option where you purchase the crysta beforehand, using either a debit card or paypal, and then this crysta is used to pay for your account. So, if I decide that finances are going to be tight and I need to stop paying for a month, I simply do not add more crysta.

Also, a note on the character creation limit: There is pretty much NO reason to create more than 1 character. At most, I'd say make 3 to see the different story lines (Once you do your first dungeon, they all merge together so no need to play the alts past that point). The armory system allows you to play as every class in the game, and in fact you're encouraged to do so in order to gain cross-class abilities.

Finally, PVP is not currently in the game, but is slated to come out in patch 2.1 later this year. Please look forward to it.