If by "not to crank" you mean the engine won't turn over, then the problem lies with the battery and/or starter cables. If you mean "not to start", then you need to ensure the plugs are gapped correctly (new plugs are not always pre-gapped) and that the wires are seated and routed correctly. Inspect the area near the plugs and wiring in case you may have disconnected something while changing them out.
Changing the plugs and plug wires correctly has nothing to do with nor can it cause an oil leak.
plugs wires
There are several things that can cause your automobile to crank, but not start. The most common cause is bad spark plugs or bad spark plug wires.
yes
No you do not need to replace any plugs at all when replacing wires.
wrong plug gap, wires on wrong, cap is cracked, timing moved when you put cap on
Yes, absolutely!See "Related Questions" below for much more about changing Windstar plugs and wires
first up i would check to make sure all plug wires are installed to the correct plugs 2 wires swapped to out of sequence plugs will cause this misfire
If the old plugs and wires were bad I would expect the engine to start and run better.
recheck wires to plugs sounds like two are crossed
No. There is nothing involved in changing plugs that requires or draws electrical current.
Check/replace Rotor Check for spark at plugs