How can I change the order of input fields in billing information page? I am setting up our store with Magento CE 220.127.116.11.
i am going to assume that this is the default code for magento v.18.104.22.168 and that you are using one page checkout. If so, then you can find the code for this Billing Section in frontend>base>default>template>checkout>onepage>billing.phtml
In that file you will find on line 44-57 the code for email and company fields, you just need to switch the block of code i marked below.
Furthermore, i would not suggest doing it on this file as it is very bad practice to edit magento core file, one option would be to create you own theme, copy this file into it and make the changes there(frontend>mypackage>mytheme>template>checkout>onepage>billing.phtml. I am not going to into the details of magento theming here as its a big topic but you can read this article to get a good idea about theming
P.S you can easily find more article on google