You seem to be asking a bunch of different, separate questions. Regarding the principal question, whether Fidel was worried that Russia would turn Cuba into a colony, it isn´t clear if he was "worried". He certainly tried to make sure Cuba never became a genuine satellite state of the Soviets.

While Russians had limited deployments in Cuba, it never became an occupied territory with self-government which merely took orders from the Kremlin. Cuba maintained an important degree of autonomy even as its close alliance with Moscow created pressure to compromise on specific issues of domestic and international policy. Fidel´s reasoning and how far he would have gone without US foreign policy driving him to cling to the USSR is not entirely clear and it is unknown when or if relevant documents will surface.

Historians, like Italian Piero Gleijeses, maintain that the fact that Cuba dragged the USSR into supporting the Caribbean county´s intervention in Angola illustrates that the island´s foreign policy was never entirely dictated from abroad. (Conflicting Missions: Havana, Washington, and Africa, 1959-1976)

A small note on another of your points. The Platt Amendment had been dropped an entire generation earlier, during the 1930s. It wasn't removed relatively recently. The memory was certainly fresh though.

Regarding the public response of Cubans, some were supportive, some were very critical. An example of the latter is Roma o Moscú (Rome or Moscow) by Enrique Perez Serantes, Archbishop of Cuba, which said that Cubans had to make a decision between Godless Communism (Moscow) or being good Catholics (siding with Rome). Operacion Pedro Pan (Operation Peter Pan) transported unaccompanied Cuban children to the US based on lies and fearmongering about the Cuban government forcibly transporting the kids to Russia or otherwise using the State to separate parents from children. As time wore on this fear of Russian penetration and control of Cuba waned, it became obvious that the State wasn't going to actually take kids away from parents, and Soviet presence (which included vacationers and those doing business on the island) just became a regular part of life. The documentary Los Bolos en Cuba handles this issue pretty well.

I'm less well versed on your last point than I'd like to be. I have still yet to dig in to Che's diaries, where I might gain important insights into how he saw things. I only have second hand summaries of his suspicions regarding the USSR. I also haven't read the pertinent oral histories which several journalists have written through interviews with Fidel where he may expound on the issue, but I will note that these are based on oral interviews with him years after the fact. When you mention Ramon, I'm guessing you mean Fidel's brother Raul. I'm unaware of even where to start on his opinions, since he really doesn't like the spotlight and I'm unaware of him broaching delicate issues like that in public.