I keep looking ot buy another freewheel or cog. I want an 18T for 3/32 chain. My Pista came with a 16T Shimano freewheel.

I am new to this type of freewheel and trying to understand them every time I fire up Google I wind up with BMX freewheels.

What Shimano freehub/freewheel do I need for a single speed bicycle and what Park tool number for the install/remove tool?

I would appreciate some guidance to get me going up this learning curve.

What tool(s) are needed to just break the freewheel down and install a new cog with more teeth.

I just cannot pull a 48X16, getting to old. I am a spinner, not a masher.

Thanks in advance!