arduino and smartphone to turn on home AC

sitzikbs:
thanks.
so how would you approach this challenge?

Don't go out and buy everything you need, throw it all together, write a bunch of code and sit back and pray.

Start with getting one part of it working and build from that. Just as an example, I would get the IR module working first, perhaps with the Serial monitor to accept commands or just a button, before even touching WiFi.