I'm not really sure on the exact numbers for the explorer axle swap but, if you check out my posts in the new vendor section Hello and Welcome to Illusive Design & Fabrications
I have the links to all of my drop components you would ever need. As for a 5" front drop you would need DJM upper and lower arms and Belltech 3" coils. This will be at about the max end of your available alignment spectrum but will be alignable by a good shop that knows what they are doing.
Most people run the DJM 4/5 kit on the 98+ rangers. This is the upper and lower arms with 2" DJM coils and a rear flip kit.
As for notching the rear, I do not recommend doing a notch on a 98+ extended cab and here is why. When the axle is bottomed out against the frame rails the big single peiece drive shaft is extremely close to the bottom of the extended cab floor. You should be able to run a 5" rear drop, trim down your bump stops and be fine with some good drop shocks. Any more of a rear drop and you will probably want a notch and you will need to notch your cab floor.
And for the drop shocks I highly recommend the Doetsch Nitro Slammer shocks I offer. I have sold tons of these shocks and everybody just seems to love them. If you have any other product specific questions please feel free to post in my vendor section or email me email@example.com