I have a 92, and while I believe the 94 setup is the same, you might want to check what the others are saying. However, my 92 will let any single din unit slide right in. Ive even borrowed my friends decks for a while (we all had the same one for a while) in times of crisis, and just popped them right back out.
You will need a piggy back(wiring harness adapter) from the back of the deck to the ford harness. You may need an antenna adapter, but i doubt it. If your factory antenna plug (big black thing on the right side of the deck, facing you) doesnt go into the aiwa, jsutgo to best buy and ask them if they have one. $9 or so for that, but like i said you might not need it.
You do need the U things to get the factory deck out, but every deck has its own removal tool, its not a matter of the housing. The metal cage is an adapter that holds the deck in the dash, and you may need to use one that came with the aiwa, since the tabs lock into that specific deck. Of course, you could probably "make" it work. Hope this is stuff is useful..ive done this too many times not to try and be helpful.