It sounds like eBay have implemented the business policies on your account, which creates a policy for each postage option you have ever used before and assigns it a generic number to differentiate between them. For some, it makes it a lot easier to set up a listing as all of their preferred options are pre-selected in what is basically a template for things like postage, payments and returns, then they just apply each one rather than going through the form, but I know it's not overly intuitive, and can create extra work for those who don't have a relatively uniform postage cost etc. You can also edit policies in My eBay, and any listings using that policy will be automatically updated.
Before I get into the rest, you can opt out of Business Policies by going to My eBay > Account > Business Policies; look for the small link at the top, right-hand side of the page (next to 'Send us your comments', and 'Help'). If using Turbo Lister, you'll probably need to re-sync it after you have opted out so that the policies are removed from that as well. This will mean your options will go back to the old way, where you go through the form and select or fill in each postage, payment and return option.
If you would like to continue using the policies, You should be able to check a box or link to show the details of a policy that's been selected, and you can also edit policies to change the options, create new ones, or even delete them. I have them on this account, and use them, but I have named them (or renamed the pre-existing ones created by eBay) so that I can tell at a glance what options the policy has (for example, one policy name is "Standard letter $2.50, reg option" which tells me that the policy includes standard postage at $2.50, and has a registered post option. When I want to use it on a listing, I select it from the dropdown menu and all is done).
Your individual policies can include the same kinds of options that are available in the standard form, but if you create one that uses calculated postage, I'm fairly certain it will have to have a specified weight and size, so it can only be used with items that match the details (eg a 20cm x 10cm x 5cm box weighing 600 grams - the postage policy created for that won't match a 30cm x 15cm x 10cm box weighing 400 grams).
I hope that helps with most of your queries, but if anything else needs clarification etc, I'll respond when I can (if no one else has ๐ ).
