2007 Kia Optima A.) Transmission B.) Suspension

I have a 2006.5 (2007 for all intents and purposes) Kia Optima EX V6 with an automatic transmission. It has just over 110,000 miles on it. I have a couple concerns that I would like to address. I have labeled them A and B to make it a little easier for anyone who might be able to help. Here they are;

A.) First, when driving at highway speeds - anywhere between 50 and 70 - the transmission will shift almost constantly, like it's going in and out of last gear and overdrive. To my knowledge, the transmission fluid has never been changed. I have bought the fluid to change it. My questions are; Will changing the fluid fix this shifting in and out problem? Since I have to drop the transmission pan, should I change the filter, also? And if so, could you give me some info on how to do that?

B.)The second issue I am concerned with is the suspension. I have noticed a 'knock' coming from the front passengers side whenever I hit a bump or go over a rough spot in the road. I am thinking it is the lower control arm bushings. I have heard other cars do this. Would changing the lower control arm bushings fix this? Or am I wrong in thinking this is the root of the problem? Also, since I have owned the car (just over a year) I have had to change the rear passenger brake pads three times, also, the tire wears slightly faster on the inside. And, when going around curves or when I hit an uneven place in the road I can feel the rear end of the car shift/sway from side to side. What could be causing this? Could upper control arm bushing fix this?