First of all, yes, 1. is a sentence. Also, you're correct that "in the" can be deleted before next Spring, and that would make the sentence sound more natural. Thirdly, I would agree that "practices" would more likely be just "practice" and uncountable like you said. However, if the speaker is talking about the actual practice meetings (in the sense that you would say "We have three practices between now and the competition") it could possibly be correct.
For the second part, I'm actually not sure, but the first one sounds much more natural to me. By saying "he had been deceived" it indicates that the deception took place in the past (which would be appropriate because the first verb is in the pluperfect tense) and also that it happened at a certain point. The second sentence with "was" sort of suggests that the deception is a state of being, which doesn't make sense to me in this case.
I hope that helps you.