Bannerghatta National Park hours are 9am to 5pm.  Avoid the Sunday rush or go to the zoo early around 9.30am. Avoid hours after 3pm -  you probably won't have enough time to see everything you might like to see. Best visited when less crowded. Eat full breakfast before start your trip.  If you're ok with junk food...plenty is available at this site. Carry bottled water.

The cost of the tickets vary depending on the type of visit - A grand safari costs you 210 rupees (including admission to the zoo). If you just want to visit the zoo, the ticket costs less. Also there is concession for children and senior citizens. The combinations include Zoo visit, Tiger+Lion Safar, Grand Safari (most popular) etc. Expats/Non-Indians pay twice the ruppees as would an Indian.

Camera fee is Rs. 25 and Video Camera is Rs. 110 (you may not want to do this). 

There is butterfly conservatory near the zoo (2 mins walking distance).  The cost of the ticket is Rs. 20 in addition to the zoo fees. 

Do the safari tour first, then visit the zoo.  Animals most commonly spotted during the safari are deer, bear, bison (not staged); tigers (staged/caged).  Bus windows have grills (criss/cross wired), for safety reasons, which would obstruct the view for taking photographs and video shooting.  Zoo has a variety animals but is not nearly as classy as one would seen in Australia, United States, Canada, etc.

Tipping guys on the safari bus - not required/neccessary.If you visited Gir National Forest, a trip to this national park could be redundant. If this is your only national park tour, it's worth a visit.