Default [Q] Installing custom ROM OR google play services on I9500 chinese version

I have a rooted chinese Galaxy S4 (original). I need to be able to download software from the google play store and have google play services on in general. Therefore, I would either like to be able to install the play store on the phone, all just install a different ROM with play store. To do this, I've searched extensively online and followed many many of the instructions, but nothing seems to work!

I wanted to install the custom ROM here -, but I am not able to get TWRP installed on my phone either. Please guide me. How should I get this done? This is really frustating me and I'm at a dead end now

Here is information about the device

Model number - I9500 (in device) I9500CHN (in download mode)
Android version - 4.4.2
Baseband version - I9500ZNUHNF1

I don't know what other information is required, since I a n00b in this matter. I will provide any information you need. Please, any help will be greatly appreciated!

Thanks a lot.