I have a 1998 Expedition 5.4 (non-eb) and I just changed the plugs on friday.
Its not the easiest project in the book. You're best bet is to just move everything out of the way that you can. Air filter hoses, power steering mount, etc. You can get by the fuel rails on the left side (and #4 is easier than #3 IMO, just not as easy to get to the plug but theres nothing in your way like there is for #3).
People say you can get #8 out on the right side without moving the fuel rail but I couldn't. Maybe my hands/fingers are to fat or whatever but since that cop is directly under the fork in the rail, I couldn't access it without getting myself a bit of room. And heck, if you pop off the rail, you can replace the o-rings on the injectors right away. That certainly never hurts. Just beware that sometimes those o-rings pull off the injector and get stuck in the rail. You'll have to get them out if they do. Don't try to force it back on because that won't work and you'll have a mess.
Otherwise, just take your time. As for the gap. I know on mine its .052-.056. | 
