I think that some of the one-off projects, like insulation, should absolutely happen. With a single outlay of time and money, you get rewards that will last for years. I have greater reservations about the ideas that may require a shift in your day-to-day life.
Your average practitioner of the art of mustachianism probably knows this, but you shouldn't buy things simply because if you end up using them, you'll save money. Kitchen gadgets are a big culprit in my experience. Gardening can be another. If cooking or gardening are something you already enjoy, then that's great and they can be productive hobbies. There are, however, a lot of start up costs and if you don't particularly like them, good tools don't always make that any better. Decent cookware makes daily cooking less bad, but I still end up just going for some veggies or cheese and crackers pretty often because cooking is still not something I especially like to do. (A big caveat here is that you don't want to go to low-end when starting some of these activities, since lousy knives, for instance will actively make cooking worse, and may convince you you don't like something that's actually alright-to-fun.)
Now if you have ways to acquire some of the goods cheaply (CL, gifts, borrowing, etc) so that you can try it out first, that'd probably be ideal. See if you actually use and enjoy that bread maker, then invest in one knowing you'll stop purchasing baked goods.