I'm happy to answer your conservation/preservation and object identification questions.
There is no practical way to determine the 'actual age' of this particular boot. You have the provenance and family history that gives you a post quem (after ~1910) date. The boot certainly looks appropriate to that period from what I can see in the photo. You could contact a textile conservator in your area using the American Institute for Conservation's free referral website to take a look at the boot and the component materials and determine if there are all from around that time. If not, they would be able to tell if they were added later as repairs. The website is www.conservation-us.org and use the "Find A Conservator" button.
For preservation, it looks like you are supporting the shape from the interior, which is good. To protect it from handling, light damage, insects, rodents, and temperature/RH changes, I would suggest finding a professional picture framer and a certified member of the Professional Picture Framers Association in your area and have them come up with a shadow box design or a small table top display. You can also find small display vitrines from University Products (www.universityproducts.com).
Please let me know if I can be of further assistance.
Please let me know if I can be of further assistance. Were you able to use my advice with your object?