Well fantastic to know that you are an engineer, otherwise, I would have been just wasting my time explaining. Now, let's go through what you have written.
1. EW and Radar has to be integrated to get the most optimal result. If they exist as 2 different components you are wasting and underutilizing your components and not getting the best out of your component. Just like the HMD and 5th Gen AIM-9x or PL-10. without HMD you gonna get a sub optimal result and wont get the full functionality out of it.
Yes one of the reasons. But this is not the PRIMARY reason why EW and Radar are INTEGRATED. The PRIMARY REASON relates to the processing power of the High Speed Integrated Circuit (VHSIC) aka the onboard computer. But Before I explain this further, just remember EW were not that sophisticated until now. As you would know, the jammers only use to jam radars, and did not jam any type of sensors. These systems are/were manual, isolated from other systems, and hard-wired. BUT most important of all, requiring a lot of onboard Power.
Now things have changed. The new generation EW is software programmable and VLSI. It interacts with the air defense systems of enemies and friends. Together with Radar and all other gadgets of the aircraft, THERE IS TONS AND TONS OF INFORMATION WHICH NEEDS TO BE PROCESSED VERY QUICKLY. The thinking behind an Integrated EW and Radar is that BEING ONE VLSI DEVICE IT WILL REQUIRE LESS POWER. MEANING A MUCH MORE POWERFUL VHSIC aka Onboard Computer can be installed. THE NAME OF THE GAME IS WHOEVER PROCESSES INFORMATION QUICKLY, GETS THE UPPER HAND. It does not matter how good your gadgets are if you do not have the computing power installed to process it quickly and gain the upper hand.
2. As I understand Spanish EW and KLJ-7 radar in block-1 and 2 are integrated to a Central Unit, through which they display their info on MFD and pilots decide how best to apply EW and in which direction to get the optimal result
EW decisions are NOW FAIRLY AUTOMATIC, and do not require too much input from the Pilot anymore. The days of pilot making decision on the direction of EW is over in the jets carrying these sophisticated systems including JF-17.
2.5. Do you know what are the protocols? It is language used by 2 systems to talk to each other. Does Pakistan has Language aka source code of Spanish EW to integrate it to Chinese Radar? No it isn't. Hence the reason Pakistan didnt go for western EW and Chinese Radar in Block-3. Both Radar and EW are of chinese origin so they can be integrated.
Why do you want to know/understand Protocols when you have components made to MIL-STD standards?? It does not matter if the manufacturers are South African, Spanish, UK, Sudan, Sri Lanka, Pakistan, Russia, US or whatever - when your products are made to these standards it simply becomes PLUG AND PLAY. Yes the manufactures will have "Access Codes" to gain access to utilize the features of their product once it is being tested or being integrated, just like password to your computer. I would strongly recommend to listen AVM Shahid Latif's interview where he clearly explains this.
You are once again misinformed what MIL-STANDARDS ARE. The Mil Standard 1553 and 1773 are Layer 1 and Layer2 protocols in terms of OSI Model which are physical and Data Link Layers.
What does it means in layman terms. You see the network cards installed in PC's and the NEtwork cables that you purchase and You connect the physical cable into network card. Have you ever wondered If you are purchasing Broadcom or Intel Or whichever Vendor network card they always connect ? Why is that? because the Cables, The network card interfaces all follow A Standard
But it doesnt mean the Network card Can WORK IN WINDOWS 10 UNLESS YOU INSTALL DRIVERS OF THAT NETWORK CARD FROM INTEL/DELL/HP etc Then network card begins to function properly
So what are the Drivers? A Software program developed by Network card developers in coordination with Microsoft. That whenever these drivers are installed in any machine. Be it Chinese, American, Vietnamese made, The network card will start to work.
So what does it all means? That there are different standards for Layer 1 and Layer 2 aka Physical and Data Link communication. Where you define your hardware, interfaces and cabling requirement that it should be standardized and whiever vendor use it in their products it, There must not be different set of cables should be produced for the hardware.
But thats not enough, Now on top of that layer 1 and Layer 2 Requirement, Now in terms of OSI Layer... And talking with Window Operating System, You need to create Drivers, That talk with the Operating system AKA SOFTWARE TO SOFTWARE Communication. Layer 7 Application analogs
Lets get back to your glaring mistake where you were saying MIL Standards are just enough to communicate. Now tell me In layman Terms, JF-17 Radar has its own Operating System, Or Drivers, Or Source code. EW systems has their own set of OS, or Drivers or Source. How will you make them communicate with each other? Unless you have a translator in b/w? or Sort of Drivers or A Middle Man who converts the language of 1 system into another system?
You may ask What are MIL Standards for? You know the physical communication that is happening over the cables b/w EW systems and Radar? That Physical Communication is dictated under MIL Standards. Cue to the physical interfaces i was talking on above paragraphs. As per MIL Standards, EW and RADAR will be using standardized Physical interfaces, Standardized Copper/Fiber cables, So connecting 2 elements inside JF-17 will be plug and play. You wont be Re designing your Hardware seral/parallel interfaces to match with other Hardware. Or producing new Copper/Fiber cables with new connectors just to connect with Non-Standardized hardware
Don't Confuse Access codes/Source code integration with MIl Standards. You can connect EW systems and Radar without any issue. Just like USB connection with LAPTOP. Plug and play but even when your USB conencts with Laptop It installs drivers on laptop to talk with LAPTOP
So where are the Source codes for EW system which will let it talk with Radar?