are you feeding this air compressor and oven from a existing garage panel ? or from your existing house panel ? or do you need to add a sup panel in your garage to feed these items ?
with the air compressor you can feed it from the panel with 12/3 romex or a conduit with 3 #12s on a 20a breaker (if using fuse's I would still try a 20a time delay fuse) a 20a breaker or fuse will not hurt any thing, as if a 20a is not big enough it will not cause low voltage,it would only trip the breaker or blow the fuse. if the air compressor ever trips the the breaker or blows the fuse then up the size to a 30a (a 30a breaker or fuse is legal on a #12 circuit that only feeds a motor) but I'm guessing / using a educated guess that a 20a over current protection will be sufficient. actually I would over kill the feed to the air compressor to #10awg wire on a 20a breaker or fuse.
now a older range will require or should be on a 40a breaker or fuse with 3 #8s feeding it. but newer ranges require 4 #8 wires and a 40a 4 prong female
receptacle & 40a 4 prong male cord end.
so I would feed the range with a 4 wire #8 range cable on a 40a breaker or fuse, but if it's being run in conduit you could get by with 4 #8s, but I personally would over size the conduit feed to 4 #6s in a 3/4" conduit on a 40a fuse or breaker, and if its a older range with a 3 prong cord & cord end on it, just use 3 of the 4 wires to feed the range. but by running 4 wires if you ever upgrade your range or use the feed for something else the 4 #6s will be there. and #6 can be put on a 50 0r 60a breaker.