I've had bulletproof coffee as well, and it's pretty tasty actually. Blending it works really well.
Strength training has been incredibly useful to me, I'm not very trim but I can lift heavy things haha. It helps a lot with your stamina when riding offroad for sure. If you're going to start lifting I'd find a trainer/coach to work with that is reputable.
Not to derail at all but somewhat on topic... if you're getting back in the gym or starting for the first time. Trainers are great to work with, but make sure you communicate if you're getting any pain. And if you consistently get pain when training, find a doctor to see! I've personally injured myself training a few times, and each time was probably totally avoidable if I'd been smarter and listened to what my body was telling me.
On diets, I personally have had a lot of success with paleo diets. I suggest trying Whole30 out and reading about the theories behind that. My most successful times when changing my diet is when I've recorded every single thing I ate, which is easier when you're not eating out.