My nearly 50 year old Howatt recurve is in for remodeling. I've acquired some bison bone and also horn material for the tips. Questions:
 Do I need to remove all of the existing tip material,( rosewood), before gluing the new tip or, can I just file a flat area on the rosewood and glue the bone or horn to the rosewood?
 Also, is super glue gel the product to use given the material I'm using?

On the tip removal you can do it either way- file it all off or just enough to make a flat area. Super glue gel is a good choice- I like the gorilla glue with the blue top.

If the rosewood is solid, still well attached to the glass, and it gives you plenty of surface area, you could flatten and glue to it.  Unless you want the looks of the wood, I personally would remove it and put the horn directly to the glass.

All cleaned up, no rosewood left. But, the surface of the limb at the tip is not flat. Do I: scribe the horn tip to the limb surface?  OR, compress the tip with a clamp to conform to the surface of the tip material?  OR....Help

I would shape the horn to fit the limb, glass has memory and will be working to return to the limb profile.

I'm thinking I might start with a hardwood then place the bone or horn over the wood. I have some scraps of osage, purple heart, wenge, and bacote.