Steven Zahm@ Pete
The costs would range widely. There are sites where you can hire a dev which can be fairly inexpensive. Code quality from my experience can be iffy. I’ve had others in the past decide to use a service like that only to end up having me fix things to for them. So you mileage may vary. In the past projects that I’ve done like this the fees were around a couple hundred. Really this would depend on what the exact specifics of the project. For a quote, you can contact me using the link at the very bottom of the page.
Yes, it is possible to create links to return results where an entry must be in the requested categories. Example:
my-site.com/directory/?cn-cat-in%5B%5D=1976&cn-cat-in%5B%5D=1981&cn-cat-in%5B%5D=2048
You would replace the numbers in the example with the categories ID numbers. Hope this make some sense!