ISIS on the offensive in Iraq

[Crandar]

Additionally, Crandar, there are still rebels in Homs generally, in towns outside of the city. From what I understand there is still rebel presence & pretty fierce fighting in these places.

As I said, they (including ISIL) have a small presence in the suburbs of the town. The opposition in the city of Homs has been completely eradicated, they didn't retreat, no. Thousands of them were either killed or captured, since the Syrian Army made a surprising encirclement.

Currently, I would say that taking Homs is the most difficult task for the opposition, with the exception of Lattakia. They are simply inexistent and keep in mind that they disastrously failed to even capture Daraa, a city very sympathetic towards sunni extremism and sunder siege by a large group of rebels directly equipped from USA.

Would Turkish control over these regions short of annexation be a bad thing?

It would be, because it would signify the ethnic cleansing of Arabs or Kurds. Turkey has already assimilated Alexandretta (having incorporated it in the early 20th century), in spite of the fact that there were no Turks at all.