For the triceps exercise, I recommend skull crushers. I recommend doing these with an EZ curl bar (same reason, it’s much more comfortable on the wrists/elbows than a straight bar) or with dumbbells (palms facing each other). These can be done on a flat or decline bench. Either is just fine. And again, if preferred, any similar triceps isolation exercise would be perfectly suitable in its place.
One of the most misunderstood areas for new bodybuilders is nutrition. I talk to guys all the time that have no idea of their daily calorie intake, their daily protein intake, their carbohydrate intake. They have no idea of what types of foods they should be eating, or when they should be eating them. They don't know what supplements do what and what they should using. Let me refer readers to some of my other articles that detail these areas.