New guy needs a hand

I am relatively new to the embroidering field but have been getting calls for patches now and then. I currently limit my patches to felt or similar material because it does not fray.
I recently purchased an old A3DW3 machine that, like most old merrow's, runs like a top. I hope to use it until I win the Lotto and can afford an MG-3U.
I personally like a Merrow stitch at the edge and am working towards that.

Question #1 is: How close can I get with the A3 machine?
I currently have a #32 feed cam in and the stitch looks great but it is still pretty broad. I'd settle for a good clean purl stitch.

Question #2. I am also wondering what thread is best for emblem edging? Cotton? Poly? Yarn? What weight?
Before investing is miles of thread I'll never use beyond the test bed, I wonder if anyone would like to share some info.

Question #3. Will a #100 feed cam actually close the stitch enough to effectively make a viable stitch?

Question #4. Does anyone have a #100 feed cam they would like to part with?

Question #5. Does anyone have a manual for an A3DW they would like to sell?

Nuf questions.

Thanks,

Mike Rieker
Dunedin, FL