Hello GLT -
You should be able to select a layout for your images when you select the template you wish to customize. These layout options allow you to configure the image locations for your listings, please try the different layouts to locate one that suits your needs. When customizing a template you would need to save different templates to hold different layouts; also note that when using a custom template you do need to select the exact number of images you wish to use in your listing, otherwise the additional slots for images do display in the template, unlike a non-customized template. Our engineers are aware of this issue with the custom templates and are seeking a solution.
If you wish to have your images in your template at a size other than the template sized images, I again will suggest that you try using the Insert an Auctiva Hosted Image tool from the description editor of the site. This will allow you to place your images directly in your description at full size, but once they are in the description within the editor you can right click on the image and change the image properties (this includes size). If you are using Firefox for your browser, you can also click directly on the images to get drag handles to change the size.
Should you encounter further difficulty, please feel free to file a support case from under the Help tab of the site letting us know the specifics of the issue and the custom template you are working on so we can look into it further.