I'm using Openlayer and GeoServer when I pan or zoom the map - OpenLayers kicks of a series of WMS requests. Does 1 WMS request = 1 tile in response. I'd have thought if you sent a WMS request with the map extents then we'd get multiple responses back to reduce the number of requests - is this possible?
Yes, 1 request is 1 tile. Getting several tiles in a single response is not possible, but if your GeoServer is serving "raw" wms'es (i.e. not cached tiles), you can tell OpenLayers not to request tiles, see the singleTile option