It all depends, but one universal truth is that we need to fuel the body with what it needs, when it needs it.

1. HIIT (wingates/sprints etc.) eats carbs preferably but run out within seconds (ATP stores etc)
2. SS (walking jogging etc.) eats carbs initially, but fat preferably
   (the maths on how much time you spend on each are simples as is knowing when you are doing each - resulting in a simple path to knowing how much carbs is needed and when, same with fat)
3. A glucose adapted body eats glucose fastest and first, from plasma
4. A fat adapted body eats fat fastest and first from plasma and stored energy in adipose tissue
5. A glucose adapted body during HIIT eats glucose fastest and first, then crashes from plasma and muscle depletion - a metabolic change happens where the afterburrn effects targets fat udring the subsequent low intensity phase
6. A fat adapted body during HIIT eats glucose fastest and first then continues to seek fuel from both plasma and stored energy in adipose tissue and will burned stored fat for hours after a session as above: - a metabolic change happens where the afterburrn effects targets fat udring the subsequent low intensity phase

Fasted anything means there is no available fuel source other than muscles or adipose tissues, still the body (and brain.... every felt foggy first thing in the am?) needs fuel, so looks to reserves such as proteins/aminos, glyco and fats in muscle, i.e. muscle itself and also fats stored in adipose tissue - fatboy slim. It works but at a cost.

So, if your body is in glucose metabolism the body knows where to go for glycogen but also gets fat, your muscles are in trouble (but also fat stores within the muscle phosphatidic acid derivatives i think or lipids/triglycerides iirc] ), whereas if you are in fat metabolism, the body knows to go directly to fat stores in adipose tissue and is in fact muscle sparing (proven).

It's actually pretty easy to see, from there, how to fuel the body when it needs it, how to have it eat fat preferably from fat stores and preserve muscle and how to prevent muscle wasting during dieting.
BUT, people will always disagree based on the status quo based upon high carb thinking.

So what about a protocol?
Based on the above, you could arguer a protocol that says,
Fueled exercise burns available glucose FAST, so fasted has no real advantage, just negatives for muscle.
HIIT is more efficient at prolonged fat burning (4 mins of true HIIT 2x per week is enough, more is better)
SS/LIT is less effective at burning fat and FAR more time consuming,
HIIT needs fuel to preserve muscle
A fat adapted body preferably burns fat as a primary source

So mathematically:
Fat adapted metabolism + HIIT + carb fuel pre/post HIIT = burn fat all the time off of training, burn glucose reserves but not muscle during training (weights = HIT too dont forget so adjust fuel accordingly), and continue the afterburn effect directly on fat during post HIIT workout window of 3-4 hours.
This is a fat burning machine and does not require fasting or does not matter where in the day/where in relation to weights it occurs as long as you fuel the body accordingly. For purposes of CNS etc. recovery needs to be accounted for and a split in sessions would be advisable, but supps like caffeine/stims must also come under the spotlight too for the same reason.

I don't know the answer to this. Most of my body builder friends only do cardio last, because of what was said above. I suppose it depends on your goals. They seem to have success with it.
I do cardio after lifting to horribly burn more fat. I've had better luck with it than doing it before I lift.
I mainly do cardio to stay healthy, especially the older I get. Again, all has to do with what you want to accomplish.

Have you tried doing cardio only on days you don't weight train? I think I'm gonna give that a shot and see how I like it. I know that after I lift, or even when I know I'm going to lift later, my heart just isn't in the cardio.

I use to think Cardio was the worst thing however I feel Cardio is great for me personally but we are all different. I like to do Cardio on days off 15 min of Hit cardio after working out abs seems to be the sweet spot 2-3 times per week. I tried doing cardio and weight training together but my body told me that it was not a good idea lol

This is a great article about exactly what you are asking..

https://www.eroids.com/forum/training-nutrition-diet/workout-exercise/fo...

Basically if you are going to do some cardio after weight training then you should drink your shake right after the weights then jump into some steady state cardio.

Personally I will drink about half after the weights and sip on the rest during my first 10 minutes of my cardio.

Cardio= the ability to lose gains

You want to be carful throwing around a filthy word like 'cardio' around these parts lad.