All memberships are for 1 year, starting on the day you join.
Although online payments go through PayPal, you do not need a PayPal account.
After clicking one of the payment buttons above, you'll be taken to PayPal.
Look for the large light blue button at the bottom of the screen, which says
Pay with Credit Card or Visa Debit (see the arrow on the screenshot at the right).
Also, you'll want to make sure you're being charged for the correct membership, and the correct amount.
You'll see the total payable at the top right. Click on the down arrow and it will show a complete summary of your order, including which membership you're purchasing. (see the other red arrow on the diagram)