Previously, iTunes took away the availability to create an iTunes US account without credit card but
it's still doable with an iTunes Gift Card.
I remembered there's a forumer which post the way to register it with a nice picture but don't know where.
As for now, I'm not sure whether you still can create an US iTunes account without credit card/iTunes Gift Card.
Do remember that you have to provide correct information for the specific state, as in their postcode and phone area code, which you could easily Google for it.

For purchasing application, some of them are FOC but some not.
But if you wanna get any application regardless of free or not, you have to create an iTunes accound of
the respective country to purchase the application on the specific conutry iTunes.
Eg. I've a US iTunes account which mean I'm liable to purchase or download anything in US iTunes.
Note the bold word.

As for tax, it depends on which state of the address that you put in your Billing Address and they will tax you accordingly.
Every state in US tax differently. NY tax 8.5% while Louisiana tax around 9.2% base on our own billing information. Do mind it's just some approximate figure.
Of course there's some state that are tax-free for digital download.
Hope that you are not too lazy to click on the previous page, we'd earlier discussed it.
It won't take you a while loading it and there's some info on this page too.
Whole list of state that are tax-free for digital download.

iTunes Gift Card, you can find it in garaga sale.
To make your life easier, Crazy.SoT.Gila are one of the seller too. Do PM him as he offered a bargain price for it.
How it works? Just like a prepaid card. You top up and there, enjoy your shopping spree.

I hope it clear your thoughts and welcome to join iPod Touch fan's club.

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Added on February 10, 2009, 10:26 pm

Ahhh, I got IS too but sadly I'm just like you, not good at sticking those stuff.
As for now, there's a lot of dust at there and I'm embarrassed to show it. 

For paid apps, you'll need to use store credits, which is attainable through gift cards/certs. Either that, or you'll need a U.S. issued credit card, or PayPal.

At the main U.S. iTune Store page, you'd see a Redeem link under Quick Links at the upper-right corner of the page.

Or alternatively, you could just click here (it opens up the page in iTunes).

You will now have a text box for you to enter the gift card/cert redemption code. Enter as provided by your seller, and click the Redeem button.

Next, a window will pop up requesting your login information. Click on New Account at the lower-left and proceed with the procedures.

For the address and phone number column, enter a random U.S. one. For the state selection however, I would recommend you to choose either Alaska, Delaware, Montana, New Hampshire, or Oregon as they do not tax digital downloads (I am not 100% sure on this, but it should be correct). If you choose other states, you'll be charged more than the listed price.

Here is a partial section of my receipt:

$17.94 is the total amount of listed price for the music/video/apps that I've purchased in iTunes Store. But due to the fact that Louisiana taxes digital downloads, I had incurred a tax of $1.66 as well. This will be deducted from your iTunes Store credit (assuming you're using gift cards/certs) automatically; you do not have to do anything to be charged

Btw, if you can't understand my steps, here's Apple's one.

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Added on February 10, 2009, 10:46 pm
Try asking for a replacement I told them that I followed the instructions, watched numerous videos, but it still went bad. Then they said that they'll allow a special case for my replacement, as usually installation errors are not covered for their replacement guarantee. Should be arriving this week
No. It'll only work with the iTunes account of the respective country.

You can still get em online