Hi rainbowdragon008 (nice handler) and thanks for your post. Firstly I'd like to let you know that your symptoms seem totally normal and very common in relation to people who do a lot of seated activity, with or without a computer screen. Gaming and tablet use perhaps contribute to the development of symptoms even more so in those beyond their teenage years. As you have pointed out you perhaps have a slightly bent over posture in your upper back, which means your neck has to extend more to compensate so your head remains balanced. The more kyphotic (bent over) your thoracic spine, the more the neck compensates, hence more muscle activity and thus more compression of the joints of the cervical spine. This positional change in the spine essentially locks off the bottom of the neck, upper part of the thoracic spine, from contributing to movement. So the rest of the cervical vertebra need to compensate for that too. I hope this is OK to follow.
Now if your thoracic spine remains bent over there is no way for your shoulder blades to drop into a more natural position. So without good thoracic (and lumbothoracic) extension they end up staying elevated and the compression on the bottom of the neck remains (this could be contributing to the pain in the little finger). So how to you approach this holistically? You need to do two things to gain mobility in your thoracic spine: firstly have your therapist/s do some releasing of those vertebrae and combine it with some releasing of the overactive/tight musculature on the front side of the body that will be resisting the opening of the thoracic movement. And then secondly, as you have mentioned, strengthen the back to provide support for that new position. Now this will take a long time as it takes years to develop the hunched position and we normally only notice it once we have discomfort. So longterm reversal take a long time and needs to be part of a lifestyle change to maintain it for the next 50 years.
One important point to make in relation to changing and maintaining spinal movement. The spine likes to move in a combination of directions. Rotation is often a combination of extension or flexion and rotation (e.g. in combination to create a side bending movement). The exercises you end up doing for maintenance should therefore include rotational movements so although you may being thinking about flexion and extension in a more passive way, ensure your therapist progresses your plan to add in rotational elements as movement becomes available.
I hope this gives you a little more insight into possible cause/effect and how to work towards a good long term goal.
regards
PB