It's now possible to search by runway length. Runways are also displayed in search result details.
To search by runway length in feet, use keyword runway. It works as any other numerical keyword, so for example
runway:10000: will look for aerodromes with at least one runway 10000 or more feet long. For each search variant
(min-max, min, max, exact) the conditions will be satisfied if at least one runway at an aerodrome satisfies them.
For more info check out the help page.
In a search result's details section, you will find a list of given aerodrome's runways, with their lengths, widths and magnetic bearings.
I'm planning to add searching for relative wind direction. You could, for example, look for aerodromes that have at least one suitable runway with a sidewind. Stay tuned.