Will a bad oxgen senor for an 92 Honda Accord LX cause my manifold to crack ?

I had the manifold welded with a bad oxygen sensor, and about 600 miles later it cracked again in a different location.

Also my spark plugs wires 1&2 pop up and there is some oil in the one of the spark plugs wells.

Will a bad Oxygen Sensor cause all this to happen ?

 

Highly unlikely.
Exhaust manifolds are cast iron, they are not the easiest to weld. If there was fault or issue with the casting there were probably other flaws as well.
Chalk it up to a bad casting and just replace it.
No.
One of three things may cause the spark plug boots not to seat.
Bad aftermarket boots, loose spark plugs allowing combustion gasses to escape and blow the boot off, and leaking spark plug tubes that have oil in them, not allowing the boot to grasp the plug.

Only use Honda OEM plug wires(sumitomo) or NGK wires.
Verify the plugs are tight.
And if oil in the spark plug tubes, replace the spark plug tube seals.

 

I gotta say, properly torque them. I can just see someone with a breaker bar tightening a plug