During beta plus decay does a proton turn into a neutron and then a positron in released?
And in terms of quarks the neutron would be: down down up and the proton would be: up up down? Giving them both 1 mass (1/3 x 3) and the proton a +1 charge (2/3 - 1/3 +2/3) = 1 and the neutron would be (- 1/3 - 1/3 + 2/3) = 0 ?
And during the decay is the positron released due to the conservation of charge before and after the reaction and an up quark is changed to a down?
Yes in beta-plus decay a proton gets changed into a neutron (so the proton number of the element decreases by one and its nucleon number stays the same) and a beta-plus particle is emitted (positron) to conserve charge (+1--->0+1+0) a neutrino is also emitted (though I'm not sure if you need to know this) to conserve lepton number.
You're right about the quarks. You could write beta-plus decay in terms of an up quark decaying into a down quark, a positron and a neutrino.