Well, first I had to research the City of Heroes VIP Starter Kit from Gamestop, since I hadn't heard anything about it. The only VIP Starter Kit I had heard of was from the NCSoft store site.
In any event, yes, you will need to set up a payment first using either a Game Time Card or Credit Card (it may also take PayPal from this page, but I'm not certain). All accounts using either a boxed version of the game (no longer produced but can sometimes be found online or in outlet stores like Big Lots) or the electronic download of the VIP Starter Kit have to set up a payment system even if they only plan to use the included free 30 days.
If you set it up with a Credit Card, it will not charge the card until your free 30 days that come with the Starter Kit ends. If you don't want to get charged, wait a few days after you start playing, go to the Billing page and click Cancel Billing.
You'll still get to continue playing using your free 30 days of VIP time and you'll be able to continue as a Premium player (Free account) after that 30 days has passed(note that there are a lot of restrictions on Free accounts), but it will not charge the credit card.
If you decide to continue playing you'll need to either have a credit card on file set up for billing (possibly using PayPal, but I'm not certain here either) or use a game time card each month.
Some people use pre-paid Visa cards from Wal-Mart or similar if they don't have access to Game Time cards and don't have a credit card.
My recommendation if you aren't sure you are going to stay would be to NOT create a character using one of the Archetypes that will be locked if you go Premium. This means don't make a Praetorian (I wouldn't recommend this for a new player anyway), a MasterMind or a Controller.
A really good resource for questions about the game is ParagonWiki and you can access it using either of the following addresses:
http://wiki.cohtitan.com
http://www.paragonwiki.com
Those take you to the same site, but use different names since they started as two different sites. There are several player tools and resources at the Titan Network using the address http://www.cohtitan.com
And of course, the players here on the forums are very helpful. There is also a Help channel available to ask question in once you get into the game and most of the people there are friendly (but some can be jerks, just like anywhere else in life).
Welcome to the game.
If the game spit out 20 dollar bills people would complain that they weren't sequentially numbered. If they were sequentially numbered people would complain that they weren't random enough.
Black Pebble is my new hero.
I see.. well, thank you for answering, the only info I could find beyond this were about threads where the OP had an account that existed before the F2P switch.... so I'm grateful for what I got, even though it wasn't what I wanted to hear.
By the way, living in Texas hi-five. Often hot, and I loathe the community I'm in, but for some reason can't seem to find the want to move. 
Okay, I've been lurking all over the internet for an answer to this.
I just bought the VIP starter thing from Gamestop, I made sure I had a new free account that doesn't have anything bought on it. (This is the only answer I could find.)
I went to put in the code Gamestop gave me, but all I got was a trip to the billing page. What do I do from there? Do I need to also buy time? (which I would, but my gamestop does not sell the cards.)
I just traded in Dragon's Dogma, (and a few other games) to do this, so excuse me If I get a little fuzzled if I find out I've been jibbed.