1)use the bottom picture - This is of designtechs web site so they show there white/black ignition 3, but on your system (Which you haven't mentioned what make/model starter you are installing) it could be called "ignition 3, ground while running, or status output"
2)If the car is a Automatic this wire is not needed, most likely you just need to ground this wire(again you didn't mention make/model of starter)
3)for the your bypass you need give up a key. So one of your spare keys needs to go into the bypass box.
4)I copied the above wiring that Stealth posted and removed the wires you won't need/use. Also for tach I always goto the coil which is located on the top of the engine, back towards the firewall. Just follow the spark plug wires back from the spark plugs back to the coil. The coil has a connector sticking out towards the firewall if I remember correctly. I pretty much test the 4 or 5 wires in there for a tach. I think it is tan w/stripe also, but I'm not sure if the stripe is yellow.
1998 Ford Explorer Alarm, Remote Starter, Keyless Entry Wiring Information
Constant 12V+ Yellow Ignition Switch Harness
Starter Red/Light Blue Ignition Switch Harness
Ignition Light Green/Purple Ignition Switch Harness
Ignition 2 Gray/Yellow Ignition Switch Harness
Ignition 3 Gray/Yellow Ignition Switch Harness
Accessory Black/Green Ignition Switch Harness (Heat AC)
Tach Tan/Yellow Coil or Pin 48 at PCM
Brake Switch Light Green Brake Switch
Parking Lights Brown (+) Driver's Kick Panel or White/Black at Switch
Hood Pin Tan/Light Green (-) Driver's Kick Panel
Factory Disarm Dark Green/Purple (-) 4 Pin Connector Driver's Kick Panel
Door Trigger Black/Light Blue (+) Courtesy Light under Dash
Door Lock Pink/Yellow (-) Driver's Kick Panel
Door Unlock Pink/Light Green (-)
Horn Wire Yellow/Light Green (-) Or Blue at Steering Column
Also, Here is a link to a 2001 explorer, at the bottom there are pictures, I know its 3 years later but its still a ford. it might help, like how to take out the key cylinder if needed.