If you live in a hot climate, keep your ac, but theres only benefits to removing your power steering, such as reduced weight, better road feel, and less parasitic loss of the crankshaft. People commonly remove 10 pounds or so of sound insulation tar on the floor using dry ice, a hammer, and a chisel. I dont know how much louder the car will be inside though.
For the ek civic there is a manufacturer making a lightweight replacement part for almost every part, from lightweight radiator stays to carbon fiber doors. Its up to you to decide which parts save the most weight for with the best price, and with the least negative repercussions. A carbon fiber hood is expensive and saves you about 16 pounds on average. You can get plastic windows from flex a lite or plastics 4 performance, they save alot of weight for their price compared to carbon fiber parts, but they scratch easily in most cases. An odyssey battery costs about $100 and, in my case, saved 19.5 pounds over the stock battery. Lightweight seats save a lot of weight, but with seats you get what you pay for. A light, carbon backed seat that is also reclinable is very expensive, while a seat from f1 spec is light, but doesnt have much padding and is non reclinable. There is a consequence for almost any part you add/take away, but also a benefit. Remember when trying to save weight the best weight to save is unsprung weight, which means the suspension and especially the wheels, tires, and brakes. The second best weight to save is up high, in the windows and roof panel. There are many other ways to reduce weight, but some of them, like removing radio and speakers, arent desirable to some people who want a steetable car.