Inspiron 3647 CPU ad GPU upgrade

I have a 3647 with a Celeron G1840 CPU @2.8GHz, 64-bit,  8Gb Ram, Windows 10 Pro. Im wanting to upgrade to a much faster CPU and install a much needed GPU. I use it for light gaming, web browsing, youtube etc.. I looked into some CPUs that are same socket compatible like the Core i7-4790 but I dont know much else beyond it fitting the socket. Will that drop in and work with possibly just a Bios update, which i can manage, or is there a better working alternative? I also have no clue what graphics card to even look into. Ive seen a few posts online pointing to the Geforce Gt640 or Gt710, then others say Gt1030. Which GPU would be the better option as far as gaming goes? Right now I only play World of Warships on it which it does ok with the settings on very low, its still playable, but im sure it could be a lot better. It would definitely have to be an HDMI port, I dont have a monitor, just my 32" LCDTV. Any recommendations would be greatly appreciated. Something budget friendly too, I dont wanna dump a ton of money into it, just enough to make it noticeably better. I also plan on increasing the RAM from 8GB to 16GB. Thanks.