(a) is fine if the summer has not yet finished; otherwise, you'll have to set it in simple past tense.
(b) 'I am' or 'I weigh' are both fine.
(c) That's a great sentence.
(d) Is not good-- I don't even understand your idea. 'Come to an end' means finish-- the movie finally came to an end after midnight', 'our holidays came to an end when I lost my VISA card'. There is also the idiom, 'come to a bad end'-- 'Jesse James came to a bad end: he was shot in the back'.
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