Applying it to the inside is in my opinion not a good idea. The leather that lines the inside of a boot is quite different than the outside leather. A good thing to remember about the inside of the boot is that it normally absorbs the sweat from your foot. The sweat contains nothing but a salt solution. Salt is a major enemy of leather! It dries the leather out. When the leather dries it cracks. I would suggest you treat the inside with a solution of water and vinegar. This solution will draw any salt that is in the leather out. I would lightly rub into the leather the leather honey. Always keep some vinegar around when you are taking care of your leather footwear. It will definitely give longer life to your leather products. How much cheaper can you go than vinegar!
I restored a 100 year old saddle that was so stiff and brittle I thought it would break! The stiffness was caused by many many years of salt from the horse and the rider. It took a bunch of treatments to bring the leather into a pliable state.. I used Leather Honey in the final stages and the leather was soft and totally restored! I hope this helps with your questions. My answer is based on my experience of over 40 years in the leather industry!
I haven't tried it on dyed fine leather. I did use it on our decade old Italian leather recliner that is "tremendously worn" and dry in all places. I had even considered sending it to the landfill, but decided to try to give it a second chance. It darkened it some and softened it lots and moistened it abundantly. It should be brushed with the paint brush from the bottom up to the top of the sides so there will not be any drip marks. It would not be a waste to order a small bottle and try it in a spot out of main site, because you can always use it on leather and vinyl belts and on non-suede shoes and on purses. I washed all the things with saddle soap and let it dry before I applied the Leather Honey. Best Wishes in You Endeavor!
If you want to retain look of boots, then no. If you don't mind making suede boots look smoother and dark like "regular" boots the yes. I wouldn't though unless desperate to have old dry suede losen up. Most likely it will just make the boots look blotchy and oily like you spilled motor oil on them.
Yes, it is safe for bonded leather. As long as the outside is made of uncoated leather. Some leather couches come with a waxed coating which prevents the "Leather Honey" from absorbing. When the "Leather Honey conditioner is absorbed, make sure you wait at least 48 hours because even though it is dry the conditioner can still bleed out on anyone who sits on the couch for a while.