You said that if you hit an insulin spike due to a poor choice in carbohydrates, that fat consumed is more likely to be absorbed as fat?
I'd guess it'd be general anabolic effects of insulin. Lipids get taken up into adipose tissue and are used in fatty acid synthesis.
Increased fatty acid synthesis – insulin forces fat cells to take in blood lipids which are converted to triglycerides; lack of insulin causes the reverse.
Yes, basically it's not of too much consequence.
Lipids are already absorbed as lipids after digestion (both as free fatty acids and in complexes with proteins) and are circulating in your bloodstream. The body has many ways to regulate them, but it certainly has to make sure you don't have excessive amounts of lipids just circulating in your blood since that will cause big problems.
Even if you had just ingested a lot of lipids without any carbs, your fat cells will still help absorb excess lipids in your blood. Insulin just helps shuttle them more efficiently into either adipose cells, muscle or liver, depending on their respective needs and your metabolic state (e.g., if recovering from exercise, insulin will drive both carbs/sugars, proteins/aa and lipids/ffa into muscles, while if underexercised and overeating it will drive them into fat cells), and also regulate other systems to anabolic mode.
Your fat cells themselves continuously absorb or release various amounts of lipids in the blood to maintain appropriate levels, so you shouldn't see the fact that some lipids are absorbed as a final terrible event, rather it's a normal everyday event.
In normal situations that's exactly the best thing that should happen, any decent size meal will still likely have more lipids than your blood should circulate at one time. A few hours later when other cells in the body have used up some of the remaining lipids circulating in your blood, your adipocytes will release more lipids in your bloodstream to maintain a proper basal level of circulating lipids.
So if your energy balance is in order (e.g. you are not overeating), you don't need to be concerned with not mixing carbs and fats, having the same calories just from fat or just from carbs will actually probably be worse than having them by a mix of both. If you are consuming excess calories, you will still gain the same amount of bodyfat from just carbs, just fats, or a mix of both, based on total calories.
But the general point is still don't overeat, and don't think of just fat or carbs in a meal, a good sanity check is total calories and things like relative proportions of proteins and fibers to fat and carbs. It's very hard to find unhealthy foods that have twice the protein than either fat or carbs for example, or twice the grams of fibers than sugars. And something with more or less equal amounts of carbs, proteins and fat is still a pretty good balance.
