If you are getting good arrow flight there is not any  reason to change anything.  You will kill plenty of deer with a 420 grain arrow.  I would concentrate on the shooting part at this point in time and worry about optimum arrow weight down the road.

Yep, just work on your form, anchor and release for three months. Then you can start fine tuning your arrows. You need to build your muscles for better accuracy and consistency.

Direct your will to learn online and study good shooting form and habits.

Ok, well when I shot it the first 50 shots it was porposing badly. Then we moved the nock point up and it flew very well. Now, this was all with a fletched arrow of course. I never had any left or right issues that we could see. Im fine with shooting them just as they are.

Yes, I'd do just that:) select the broadhead weight you would like to shoot. I'd say 175-200 will leave you with the most options.
Then just bareshaft using the field point (never BH) and cut from the nock end 1" at a time. You should end up cutting those shafts down to about 28"