Good detail Bob.
To answer your first question, what doe it take to put a 5.0L in a Ranger - research. Do some reading on the threads Bob posted and spend some time searching this board and the RPS board. There is alot of information on those pages. Also, are we to assume it is for your 2004? Are we to assume you are planning a stock explorer 5.0L or do you want something different, like the free 86 5.0L you got from your uncle's F150? Detail are necessary.
Anyhow, enought ranting - read up on the threads Bob posted and come back with any detailed questions you may have. We are happy to help.
DD: 2010 Sport Trac Adrenalin. 4.6L V8 / AWD with Terra Grapplers and Voxx G-FX wheels.
Toy: 1999 Ranger 4x4 4Door. Replacing 302w 1.5L Kenne Bell with a 351W: Explorer EEC-V DIS, AFR205 heads, custom 1 3/4" long tube headers and Autorotor 2.6L supercharger, intercooled with '03 Cobra and custom fabricated manifold.