Do you know how dry it is? If it's given back reflex easily, it may need further drying. A hotbox is best, but a car/ attic can work as long as you keep an eye on the upper heat limits with a thermometer.
Since ya got a heat gun,you may want to add more reflex before tillering more. My first staves were probably not dry enough = string follow when I was done, wished i had added more reflex
I'm no expert, but your first effort seems to be going great - beautiful stave, too.
Tools:
-A stanely shureform works good, but I prefer a rasp.
- Hit the fleamarkets / yard sales this summer, especially near farmland areas, and getcha a good drawknife. This bow's gonna be good, so you'll be getting osage logs at some point!
Lotsa Luck,
john