What are the different ways to link from my site to the private label site?
Is it possible to use XML and then link into the private label site when the customer wants to book?
There are various different methods including putting search wizards, deep links and banners on your site. See some examples here.
Yes, in fact many of our affiliates like this option as it provides more flexibility to control the user experience during the searching process but avoids the hassle of having to build the secure e-commerce pages to process the transaction.