I don't use ramps, I use hydraulic jacks and jack stands. But an Explorer is kind of high so a 12" jack isn't going to work. Maybe for basic service the ramps are enough, just don't drive off the edge.
Creepers are a goddamn pain in the ass. I have owned several, they never roll well. Just save your money and get some large cardboard boxes. Open them, lay them flat, crawl around on them. Flop on yer back, grad the frame above yer head and slide on under. They also keep the driveway clean.
Get some basic tools from Sears. You can afford them because you won't be buying a creeper and big boxes are free from the appliance stores. Explorer plugs would require a 5/8" spark plug socket. Get a plug gapper tool. get a damn good oil filter tool. You want the filter to come off. It sucks when the tool won't work and you have to drive a screwdriver throught it.
Get a good drain pan. A large one. Stuff does not always drain straight down, especially when the wind blows.
Search online for a scanned manual. I have downloaded manuals for my Midget, my Kawi KZ400, my Volkswagen diesels and others. Just keep searching for Explorer Ford manual download and see what you can find. Also, check Ebay. I get manuals there too.
Check out the message forums.
http://www.ford-trucks.com is a good one. By reading the posts and searching you will find hints and tips about things like changing the plugs and stuff. Plugs, distributor cap and rotor, plug wires, oil & filter. Done. Air filter-- is it old? PCV valve will last a long time.
How many miles?
As stated, auto parts stores will accept your old oil. Save some milk containers to put the old stuff in.