As mentioned the black smoke is because the poor old girl is knackered and really really needs a refit, even merchant ships rarely make as much mess, (usually only when they switch from diesel to heavy fuel when going into or leaving port)
The russkies have had a lot of problems with their carrier based planes as well, only about 35 of one type got made before they finally gave up on it and the other has had serious issues.
I suppose this trip is to show solidarity with Assads Syria in the Med and produce some feelgood propaganda at home. The russkies aren't really sailors IMO but they're a tough bunch and will work hard to make everything work.
That tug is a good idea, a handy emergency boat plus an insurance policy if your engines go tits up, as was happening to the newest Royal Navy types in the Gulf last year.
If they get any serious issues then she can always limp into the Black sea