In my experience lower reps and higher weights will definitely make you stronger, but not necessarily much bigger. Obviously you will grow but not to the extent that reps in the 8 to 12 range will. If you want size then I'd definitely recommend 8 to 12 over 4 to 6. You should try to mix it up over the course of a year anyway. But while on this cycle you should probably prioritise what's most important to you.

Yes, the AAS will help whether growing big or strong. but as you're using test E you need to appreciate that you can't suddenly up your volume and weights etc from the first pin. It will take time for the test to work. Use those first few weeks to slowly and gradually up your work load. You don't want to blow out just as the test kicks in.

Just be sensible. It's not going to turn Danny DeVito into Arnold Schwarzenegger overnight!

ps I agree with Pullstrong that changing style whether bulking or cutting is not the answer. That's down to diet, not training. If you want to grow big or strong you need to eat. If you want to cut body fat you lower calories. You can cut using 4 to 6 or 8 to 12 just as easily.