I would also suggest, if it is a real motivator for you to be keeping the idea firmly in your mind that you will be able to live a normal long lifespan if you lose the weight, by all means, keep it firmly in mind. When we're changing our diet and exercise habits to be more healthy and lose weight, we can use all the prompts we can think of to give ourselves. Some people want to look better in a bikini, some people want to be able to run a marathon, some people want to live to be 70 or more, it's all good because it's all motivating. Pick the one that has the most emotional resonance for you, and use it to help you on your weight-loss and health journey.
We have a family member that spent many years clinically obese. She had gastric bypass surgery and lost over 100 pounds. This was in essence to save her life. She very soon after had a complete shift in her numbers from her type 2 diabetes to her blood pressure. Losing the weight will greatly improve your health and likely prolong your life. As to how long you'll extend your life, no one can say for sure but would expect normal life expectancy at that point. I so hope you make that choice. :>)) My family member is in her sixties now.
Does it matter? Staying obese will keep producing more and more problems as you age, so you will benefit from it even if it doesn't reverse all negative effects already incurred. However, there isn't any guarantee that you have suffered any damage yet -- obesity affects different people differently. There is evidence that obese people don't actually live significantly shorter lives than others, but there is considerable evidence that the life they live is much harder and much more challenging. As for that loose skin thing, maybe, maybe not. You're still pretty young, and one way to reduce the loose skin problem is to embark upon resistance training as part of your exercise program. This will give you more muscle tone. Now, you will have to keep doing resistance work the rest of your life, or as long as you're able, because when you stop, muscle too can turn to loose skin as it deteriorates. Make sure at your weight you get professional advice on an exercise program so you don't overdo it and harm yourself -- both with your dietary changes and exercise changes, and you'll need both for long-term weight loss that stays off, you need to start slowly and work up gradually until your fitness level can handle it. But again, your question isn't really the most important one, as you will benefit no matter what. Best of luck.
I would think so. You might find you have excess skin that someday (given your maintenance of the weight loss) you would possibly consider removing surgically, since skin cells once put on do not go away. But many of the physical insults of excess weight do go away when the excess weight goes away. Your heart will thank you, your knees will thank you, your lungs will thank you. Your entire circulatory system will sing your praise. :) Good luck, it sounds like you can do it.