2011 Prius help with P2238 P0240

Hello I am new at this would really love some help. I recently purchased a 2011
Prius with 176000 miles I know it needs work done, I know it needs a HV battery
Witch I will buy only if I know that I can fix these issue with these 2 codes. Code 1 P0420, code 2 P2238. Also was having the light on for cooling temp only while in the express way 65 to 70, after reading on hear that most common was air I checked the car while in maintenance mode and found that the thermostat would not always open had to squeeze hose to get to open I've ran the car for some time after squeezing the hose and may have help with air in system. I know I'm all over the place with my words. I will be replacing the fallowing items spark plugs, PCV valve, oil change, thermostat, while doing all that will be cleaning intake manifold, egr and cooler
also be adding oil catch can also purchase upstream O2sensor denso
My hope is that the cat is still good and that after going all the work I can buy a new battery anny advise would be greatly appreciated thanks