Is there any blame on the questioner for oscillating between the sayings of scholars regarding the issue of declaring one who abandons prayer an apostate, or for disseminating these sayings when he used to follow them?

It is permissible to adopt the fatwa of a scholar that was not previously known, and to disseminate what is deemed more likely correct from knowledge, and then to retract it later after an increase in knowledge. It is permissible to follow the madhhabs (schools of thought) and to switch from one madhhab to another under certain conditions: believing in the knowledge and merit of the one being followed, not seeking out the concessions (rukhsas) of the madhhabs, and not combining between madhhabs in a way that contravenes scholarly consensus (ijma'). Consensus has been reached on the permissibility for anyone who embraces Islam to follow any scholar, and to switch from one mufti to another. Furthermore, abandoning prayer out of laziness is not considered disbelief that expels one from the faith according to the majority of scholars.