If your using asphalt shingles, a coating is not necessary. You want to start with 50 lb. roofing felt unless you're laying on top of the old roof.
A cheap Porter Cable compressor will do fine...
https://www.lowes.com/pd/PORTER-CABLE-6-Gallon-Electric-Pancake-Air-Compressor/4764588?cm_mmc=SCE_PLA-_-ToolsAndHardware-_-CompressorsDiyAndStationary-_-4764588:PORTER-CABLE&CAWELAID=&kpid=4764588&CAGPSPN=pla&store_code=3095&k_clickID=9ad8cc19-1d7f-43de-b203-f066a153f524&gclid=Cj0KCQjw3InYBRCLARIsAG6bfMQK5c4ispX7SCzq3ZD82JDdm_tGdixU2HLzavwtgjZoX0r2ewWQ5rIaAvAOEALw_wcB
I like the Hitachi roofing nailer, and it's price squarely in the middle of the pack...
https://www.lowes.com/pd/Hitachi-1-75-in-15-Degree-Roofing-Pneumatic-Nailer/1069793