Here's my 2 cents. First, hold off on the trainer cord until you know what radio your instructor uses. Futaba has 2 different styles of plug and you need to have the right cord. If he's got a JR, the cord won't do any good at all.

As for practicing on the sim, I discourage it unless you get some tips from an instructor. It's just too easy to get really good at doing things wrong and then have to unlearn them. However, some people do train with the sim and seem to do ok, so it seems that there's no absolute best choice. If you are going to train on the sim, work on the basics such as keeping the plane straight on the takeoff roll, let it build up enough speed before taking off, shallow rather than steep climb outs, smooth turns, etc. Also work on landings by lining up straight with the runway, use the ailerons to keep the wings level, and rudder to make minor course corrections, and if it seems you're landing short remember that increasing throttle, not pulling back on the elevator, is what's going to get your plane home.