First and foremost, thank you for your reply.
(a) Do you think this pain in the deltoid area will go away or is this permanent damage(do u think it is a serious injury or just a minor one that wil heal with more time)? The reason I ask is because it has been 4 and a half months since I injured it and I still have this slight pain. It really concerns me this slight pain because i dont want to start working out again and then permanently stuffing it up, unless I already have!
Did you see a Physio when this happened? Acute Ultrasound treatment may have helped microscopic soft tissue repair and alignment, as well for both Ligamentous and Muscle/tendinous tissue. At least some evidence suggests this would be helpful in acute injury.
Weightlifting injuries take specific rehabilitation for full recovery. Just letting it rest and atrophy (become weak) will not help you recover any quicker. I would be very cautious of working out on the injured shoulder without appropriate adaptation, intervention and consideration of the structure at fault. It will just end up being a longer delay
No, I didn't see a physio at all. I made the mistake of reading over the internet that the pain will subside and also taking advice from friends who said that time will heal the pain. While the majority of the pain is gone like i said there is only slight pain coming when i bend my arm at the back of my head. I am sure that this is from that rotator cuff injury. Is it too late for that Acute Ultrasound treatment?

(b) Should I start strengthening my Wikipedia reference-linkrotator cuff even though i have this slight pain?(I have been taught the exercises i need to do to strengthen it)?
From where have you got the exercises, have you had an assessment done. It could be that you are not getting pain from the rotator cuff itself. Other tissues underly and cross over this joint.
My mates have shown me exercises that I need to do to strengthen the rotator cuff and i have found some over the net. The exercises involve using dumbells and are used to strengthen the rotator cuff. Apart from that, no assessment is done.
(c) And the main question. How long after the injury can I start working out again. Can i continue to work out now, 4.5 months since the injury or should i rest it for longer as i still have slight pain?
There is no reason you can not work out, but I would be very cautious of going back to doing what you are doing. Any movements that cause pain or discomfort should be avoided. You could for example3 work out legs with no issues in the rotator cuff region. I have had similar issues in the past, and have discovered the only way to get back to full fitness is to properly implement and treatment and management program.
Yes, I did that for a while. I did cardio and some lower body work but my mainfocus was on upper part of my body and since i got injured and figured i shouldnt work out i stopped working out altogether.

I know I will need to go see a physio soon and stuff to get this scanned but from what I have described what sort of injury do you think i have? Is it just a minor problem or a really serious one that will require surgery? And the main question, i know you don't know the answer to this because you dont know what is wrogn my shoulder but can these rotator cuff injuries be 100% healed. I mean it felt like a pop out/in and i still have a bit of discomfort(it looks as though its coming back from the back deltoid area) so is this something i will have for the rest of my lift and wont allow me to work out ever again? Thank you again for your time.