My DS1 has a diagnosis of Tourettes with OCD and generalised anxiety. I was actually looking at the Tourettes Action website today and reading about the variability of Tourettes: you can have 'pure Tourettes', 'full-blown Tourettes' or 'Tourettes Plus'. My DS has the latter. I'm afraid there is no way you can know what your DS will develop, as it is very variable.
In answer to your questions: school was very difficult for DS and he developed extreme anxiety about going to school when he was nine. We struggled on for a couple more years, but I had to take him out in Year 6. He tried secondary school, but it was disastrous and so he is now home educated.
The tics have never been a problem, although, of course, they were embarrassing for DS. The OCD and anxiety have been far more of a problem and the reason why DS can't go to school anymore. Interestingly, as DS's OCD got worse, his tics reduced and now they are hardly noticeable.
DS has had a lot of ups and downs with his friendships. He can only cope with one good friend at a time. Groups are too much for him to deal with. He has been the victim of bullying.
Yes, it is possible to have just the tics (this is 'pure Tourettes'). There is no way of knowing whether your DS will develop more OCD-type behaviour over time, I'm afraid.
My son's tics were very bad during primary school, but they are very subtle now. Adolescence is meant to be a bad time for tics, with them improving in adulthood, unless you are one of the unlucky ones with severe Tourettes.
My DH has Tourettes, although we didn't know until our DS developed symptoms. Nobody would ever notice his tics because they are so subtle and he makes sure that he keeps them under control.
When DS's tics were bad, I would usually ignore them. However, we did sometimes find that laughing about them helped. One of his tics, which he found mortifying, was a kind of Nazi salute with his right arm. We had to laugh at that one because it was so inappropriate.
I hope the appointment with the neurologist goes well. Best of luck.