Hi
Delete some apps on iPhone 5 get then back later on new iPhone
Go to settings make sure iPhone 5 is on ios 9.0.2
The go to iCloud on iPhone back up now
After that set up new iphone 6s do this over your WiFi
Use same Apple ID to get your apps /data back.
Before you start you could always buy more iCloud Storeage .
I always use WiFi haven't use PC for iPhone / iPad
For 2 years use WiFi .
Cheers
Brian (uk)