The version утром is quite neutral and simply means 'in the morning' or 'this morning' while с утра can have 2 different accented meanings:
1) (to do something) first thing in the morning;
2) (to be in condition of doing or not doing something) since (the early) morning
Correspondingly, your sentence 2 (which uses утром) sounds more natural than sentence 1 (which unnecessarily emphasizes awakening as the first thing done in the morning). I'd also slightly adjust the word order (to neutral) and add a preposition:
Сегодня утром я проснулся примерно [в какое время?] в без четверти
The sentences 3-7 are all possible, they vary in exact meaning (in the morning or first thing in the morning) and (due to diff. word order) emphasize different aspects, e g. sentence 4 emphasizes time aspect (as if it's a complete answer to a question about time), since in neutral case (sentence 5) time words in Russian are usually close to the beginning of the sentence (they are typically not in the end of it as in English).