I browsed Wikipedia and found out that leadership of the Latvian SSR was predominantly Latvian, not Russian.
There is a nice Russian word to describe it - показухa.
The real leaders were in Moscow.
So in which respect were Russians more equal than others in the Latvian SSR
Not Russians, but Russian speaking migrants from the rest of the USSR.
Because Latvia and other Baltic states were colonies of the USSR.
And immigrants came here to colonize our land.
That's why they had privileges - better job opportunities and faster access to cars and apartments.
They settled mainly in largest cities and towns - for local Latvians it was problematic, because of propiska system - thay had to stay in rural areas and smaller towns.
(Of course some Latvians got apartments in Riga too, but immigrants got them faster than normal queue - that's why some areas of Riga that were built during Soviet times (including area where I live) feels like Russia.)
So this is a bullshit argument that Soviets built houses, schools, infrastructure and factories for Latvians - they built these for Soviet migrants.
Late 1980s protests against Riga metro was not because Latvians do not like rapid transit (It is a pity that it was not built), but because it would mean even more immigration from the USSR.
Military, police, OMON and KGB officials had even more privileges - they were basically above the law. (Many were sent here from the rest of USSR to keep colonies in check)

Now "former" chekists, former military and criminals are forbidden from naturalization. (Russia should have done the same with their KGB officials and communist party members)

State Language Inspectors spying on and harassing members of a national minority going about their daily business.
You are trolling. That might be some Latvian radical nationalist's wet dream - thankfully that's not the case.
"Language police" only act if someone complains - it is more like customer service quality control.