and you need to eat like a man possessed.
That is one of the most confusing parts... A friend of mine who competes as a strong man mentioned this to me also, but he has what LOOKS like a beer belly. I'm sure it isn't bec i don't think he drinks and he has been lifting and competing for quite some time.
Is there a certain percetage each day i should be getting my fats, carbs, and protien out of my total calories? How many calories should i be shooting for in a day? I currently weigh about 178, i'm 6'1", and do a 2 day split push/pull. So i'm in the gym lifting 4 times a week and doing some sort of cardio 4-5 times a week.
strongmen don't care about their physique, they only care about their strength so they try to stay in a massive calorie surplus.
You won't be eating as much as they are, and if you do find yourself getting fat then eat less.
Don't let fear of getting fat make you undereat. You'll never get big that way.
And i have also heard isolation exercises are better for building size. Is that true? Or could i build just as much muscle mass doing squats ad i could doing leg extensions on a machine?
No. Isolation exercises are the icing on the cake. To use legs as an example, squats would be the focus of your workout, and most of your size will be built with them. Once you've done your squats, you'd add some isolation exercises to bring up certain areas, eg leg curls to bring up your hamstrings, extensions to emphasise portions of your quads etc.
You'll find that the compound lifts will favour different muscles depending on your physiology. For example, I am quite a delt dominant presser, so my chest doesn't get fully stimulated benching. I can do an iso exercise for chest after like pec deck or whatever to make sure all my muscles are getting worked properly.