wow, so may different answers...anyways I'm just gonna touch point number 4. infact it was answered by thunderfoot for point number 3

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no wrong in this, your tendon will eventually become stronger and thicker as the result from strength training, muscle grows along too. reason to cause injuries is bad form while performing an exercise.
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To recover from a surgery or injury, strengthening exercise is part of physio therapy, normally you do resistance, and not heavy weight.
DOnt do by your own without consulting a physio