Virtually all campground hookups are the standard 30 amp connection that will fit your Airstream plug. Where there is 50 amp service, it is in addition to the 30 amp service in at least 99% of cases. In fact, most campground boxes have all three types of receptical.
You should always carry the adapter to plug your 30 amp plug into a standard household outlet type. You can then plug in at home. I have found a couple places over the years where the 30 amp service was kaput; the adapter allowed me to plug in to the household type socket without moving the trailer to another site. A 25' 30 amp extension cord is also a good idea to carry. I have been able to get service from an empty adjacent site when the service failed at my site.
Water connections are a standard hose bib. Don't use your garden hose; use one of the white RV hoses to preserve the quality and taste of your water supply. Garden hoses leach chemicals into the water. Also, get a pressure regulator and put it on the end of your hose where you connect to the campground supply. The regulator will protect your hose and your trailer from over pressure in the campground supply. I carry two 25' white hoses.
You should carry at least two 10' sewer hoses; better yet, a 10' and a 20' hose. A lot of campgrounds are poorly laid out.Pay a little extra and get the better quality hoses; the cheap ones just do not last. For connections, you need the adapter to attach to the trailer, connectors to attach hose to hose when you need more length, and an airtight connection to the campground pipe. Some places will require a foam collar or screw-in connection by campground riules or local ordanince. I use the blue twist-on connectors I get at Camping World.
You might look at what is available at http://www.campingworld.com