Is it worth to buy JR pass for 16 days and is it cheaper to buy normal ticket for last 4 days in Osaka?

My 16 days Kansai Trip:

Osaka station: 1 night
Kyoto station: 3 nights
Amanohashidate station: 1 night
Kinosaki station: 2 night
Tottori station: 2 nights

Okayama station: 1 night
(San-yo Line 1hr 25min)

Himeji station: 1 night
('A' Tokaido-Sanyo Line 36min)

Kobe station: 1 nights
('A' Tokaido-Sanyo Line 26min)

Osaka station: 3 nights

1) Is it worth to buy JR pass for 16 days ?
OR is it cheaper to buy 2 Kaisai Wide Area JR Pass (5 days x 2) + normal ticket for last 6 days?
OR buy 3 Kaisai Wide Area JR Pass (5 days x 3) + normal ticket for last day travel to airport?

2) Kaisai Wide Area JR Pass can use for JR Super Hakuto train from Tottori Station to Okayama Station?

3) Kaisai Wide Area JR Pass can use for 'A' Tokaido-Sanyo Line?

3) What normal train ticket to buy for travel from Osaka Station to Kaisai Airport?

Thank you:)