The minimum you will need to do is make the outside loop all 048 curves. Big locomotives, like the DD35, look and work better on large radius curves, so go as big as you can.
The power supplies that came with the Lionchief sets are okay for them but if you are going the run other locomotives, lighted cars and accessories you are going to need more power. Transformers are not cheap but are critical to your operation. Overthink the transformer size, bigger is better.
I'm not sure where you got this layout plan, so I do not know if you got a wiring plan to go with it. Since you are new, the simplest connections you can make are to attach one power supply to the inner loop and the other to the outer loop. To isolate the two loops disconnect the red wire on the fitter piece of each of the two 048 switches on the outer loop that connect it to the inner loop (the switches that lead to the crossover)..