Man, I've never been in the same position as you but I have been lifting for a minute and have made my own personal growths and changes over many years. To some it may not seem like a lot, but I have came a tremendous way from where I started.
The best advice I could give you, and anyone else, regardless of the goal at hand-- that is to make gradual and slow changes to your lifestyle. Nothing should be a chore. Every little thing should have a purpose and it should be something you want to do. Even when it means making sacrifices elsewhere in your life, it won't bother you because you want it to be that way. It won't take the massive mental effort people portray it as, because you'll have so much passion for the goal or the purpose that it just won't matter.
Whatever your goal, I believe in having a mindset that you wake up with everyday and you don't feel like you need to explain it to anybody--because it is you and again, you want it to be that way. I would never have anyone look at my lifestyle, my lifting, my eating, or my habits and then tell them "this is how you have to do it." Because, the way I am now is a large product of many, many small changes I have made a long the way. It has all added up. I would suggest the same to you, or anyone else. Small changes over time, be persistent and effortlessly want whatever it is.
To specifically answer your questions...
Supplements are not necessary at all. It is all about your diet, and eating to meet your goals.
When it comes to exercises, nothing beats squats, deadlifts, rows, dips, pull-ups, overhead pressing, sprinting. I assume you're doing them with the 5x5.