You have a solid base to work with. Its better to start off smaller than overweight, I believe. I started off as a skeleton but it means youll likely gain more quality muscle than fat for a while. Even if bodyweight gains are much slower than someone with a slow metabolism. Once you hit 30 that will likely change anyway. My metabolism was lightning fast in my twenties and teens, once I hit 30 it slowed drastically. I used to lose 5 lbs a day if I didnt hit over 4000 calories. Even at 6000 it felt like I was moving backwards often.
You dont need to focus on supplements. Main thing is going to be your food intake. Supplements can add to a solid diet, but its a very low percent that they add in terms of strength and size. Anabolics are a different story but its not good to use until your natural test levels get low. Maybe around 30. And with anabolics you are looking at alot of issues. People dont realise the psycological part of going on anabolics. Once you go off you can easily lose the motivation to train at all while off. Since you have no experience doing it without. Also the possible shutdown of your natural test can make you more reliant on the shit. Once you go off you start losing much of what you gained on it. So its not really a shortcut.
Store bough supps will give you a very minimum edge at most, and most are bullshit. Beta alanine is good for muscle endurance and creatine monohydrate as well. Caffiene its not really good to get hooked on, because thats another thing you can become reliant on.
The main thing is going to be getting in enough food CONSISTANTLY. Consistancy is the hardest part, especially with eating. Dont be afraid to eat more, to force feed and gain some fat. When you want to lean out its better to do it seperately. You will likely not be able to gain muscle and lose fat at the same time. Not even worth trying. Focus on one thing at a time. Dont try to lean out too often are you will be constantly making steps backward in your progress. It takes years of straight training to gain a good amount of size. You dont need any interruptions by leaning out. Better off saving that for way down the road, if needed.
High protein, high carbs,etc. The amount is dependant upon the individual. There are many cheap and non cook food sources. Milk, peanuts, seeds, cheese, peanut butter, yogurt, etc. That can boost your nutrition between meals. The number of meals doesnt matter, just getting it all in by the end of each day. Take in enough to continue moving the scale up at this stage. That should be a good indicator for now since your metabolism is likely pretty fast at this point.
KILL THAT SHIT !!