last year i stay only at Osaka for 8 days
but it was free and lazy trip. wake up late, breakfast then only go out

spend average about 4k for food and transport and shopping.
hotel and flight is not included

railway from osaka station to kyoto about 45 min average depend which type of train you take

if you want to save on travel time better to stay at Osaka and Kyoto
do not stay on just one place

i stay 10 min away from Osaka station
most of tourist attraction place are connected with train
and bus also.

try open up google map and see where you plan to stay and where is the nearest station

peak hour, you may need to cramp with ppl to work