a)There wouldn't be a "massive army sitting in Salonica" had Greece not allowed it in 1915.
b)After 1916 there was no Greek Army for Sarrail to clash anyway.
c)Had southern Greece hypothetically possesed an Army, and had it decided to side with the Central Powers, the Entente armies around Salonica would be sandwiched between Greeks and Bulgarians. Also, that would consitute a Civil War for Greece, as Sarrail's command included the Greek National Defence army in Salonica and the islands.
2)There is no such thing as Germanophilia. There is Grecophilia.
1) They "allowed" it via gunboat diplomacy, no more and no less.
2) Citation needed.
3) Sure there's such a thing as Germanophilia. You see it all the time in alternate history.