I will be pouring a concrete patio next week which will be 10x12' and everything I see states the control joint needs to be 8-10' apart. Should I place joint in center from each direction? The patio will only be for foot traffic and no cars will park on it.
Also, I dug out the earth so the patio will be flush with ground when complete and used 1.5" of #57 gravel as base and will pour ~3.5-4" of 3000 psi so is rebar or mesh needed? I have rebar from the last step on concrete stairs so it will hold to new patio but thought gravel base would be OK for this application?
Unless you can live with a random crack or two running through the slab, I'd suggest adding a joint in each direction. With today's rapid setting & curing cement, especially at the height of summer heat, I tend to make 8' x 8' max. squares for a 4" thick slab. You could possibly get a way with the 10' x 12' with no control joints with the right admixtures & curing process, but you'd certainly be safer to add the joints.
As fro the re-enforcement, I would use whichever one was easier for you to attain & handle. Some here will tell you that it won't work because case studies performed on bridges, roads, The Hoover Dam, yada-yada, say it won't work ideally in a 4" thick slab. 20+ years of on the job assessment tells me that concrete re-enforced with steel performs better long term than concrete without.