Reactor Heating & Electrical Consumption For The Reactor Stirrer

(1) I need to heat a mixture of organic compounds from ambient temp to certain reaction temperature(known value). Mass of the mixture, heat capacity of the mix, total heat to be supplied are also known..

Heating is to be done in a reactor, heating media is Therminol. What should be the flow rate of heating fluid? Is there any thumb rule for minimum velocity of heating media in tubes? What are basics for designing such types of reactors?

(2) How to calculate the electrical consumption for a reactor (polymer) stirrer? Melt viscosity (in PaS) and bulk density are known, also if required an arbitrary value of rpm can be assumed.