Setup right field type and widget for field I'm using Drupal 7.23 to build an online catalog for a shop. I made an "articles" content type and I've built all the required fields. 
I need to setup the Price field in a way that it's a list, and each row of the list will show something like "buy x at yx", like "buy 1 at 5, buy 2 at 9, buy 3 at 12" and so on, and I need it to be treated as numbers (5,9,12). How can I accomplish this?

I have also the image field, I need to have up to 10 images for the same article, and I want to show a gallery (more or less like Amazon does), where you click on the photo and it enlarges. It is handled by Drupal already? Do I have to setup something special to do this?
For the first issue you can actually add it as a key|label pair. 

Where the key would be the number and the Label would be what is displayed. for example 5|buy 1 at 5 

this would show "buy 1 at 5" in the dropdown but the value would be five. you want to work with numbers you might want to select List(integer) as your field type. 

For the second problem you might want to take a look at the Cloud Zoom Module.


  This addon provides a small, thumbnail sized image, with an on-hover
  popup, zoomed and centred on a larger version of the image.


OR 

jQZoom


  The jQZoom module is a wrapper for the jQuery plugin jQZoom. The
  module provides a javascript magnification effect for images. When a
  user mouses over an image, a larger version of the area under the
  cursor will be displayed beside the image.