I will assume you mean to say "called", not "calle".
1a & 1b & 1c are all valid. But 1a is more natural & classy. 1b is low-class, juvenile English. 1c is awkward, similar to 1b, but in the case of "whom", is an unclassy speaker trying to appear posh and failing.
2a & 2b are both valid, and have slightly different meanings, but are both complex awkwardly worded sentences, I would move the word "indeed" and I would make use of commas at least once in either of these sentences - but this is not a strict requirement for grammatical validity, it's just an improvement for clarity. Both instances of the word "it" do indeed refer to the watch tower, but "as" and "which" refer to the name of the watch tower, not directly to the watch tower itself.
3a & 3b: Both are valid, but some people will say "was" should be changed to "were" in order to match the tone of the rest of the sentence, especially considering how the word "had" is used here. However, I will not say "was" is invalid - I will only say it's casual/informal (borderline sloppy) but very common form of English; while the use of "were" here is an extremely classy, posh, highly educated way of speaking.
The meaning of 3a is as follows...
My father had a great character (generally referring to personality traits like integrity and charisma). However, it's been a long time since he could relate to what it was like to be a boy.
So your guess is close, but not precise.