I changed the motor pulley to a smaller one on my 80 gallon compressor. It lowered the RPM from 1200 to around 800. Its very noticeably quieter, and I know the compressor is going to live much longer. Yes you will lose some CFM, but I doubt you will run into any issues with that. My compressor...
Yes... On a pour that large those cracks are normal.
The re-bar you installed will not stop cracks, what it will do is keep the cracks from opening up and keep the slab from getting elevation changes between the cracked pieces.
As already stated the only cost effective way to avoid (hide) most...