for/on? I'll ask him when he drops by for/on a cup of morning coffee. Which one is correct? Thank you!

Are these two sentences grammatically correct? 1. We can sit here now and discuss all the ways in which this can destroy our friendship or we can just do the right thing. 2. He thinks about the time they hid under the old stone bridge, empty paper cups and persistent-still-autumn leaves crushed under their hips and their fingers, and Jane's nose was cold, winter-red, and John remembers how her lips tasted like crisp snow when he kissed her.

Help with three sentences? Are these sentences grammatically correct and would you say them differently maybe, in order to sound better? 1. But she can’t hide a knowing smile as she watches how Joan closes her eyes, nose tucked into the front of her father's shirt. 2. The world is different here, loud, full of men and women with funny hats and children clutching brown paper bags in their hands. 3. He doesn’t like this grown-up voice James has developed lately, it always turns jokes into something serious without anything specific ever being said.

Is this sentence okay? When John woke up on the crisp morning of December 23th it was way too cold and he had grown rather fond of his toes to lose them in such a careless way as getting up from a warm safety of his bed clearly was.

Help with a few more sentences? Okay or no? (: 1. This coat is dirty with dust and mud. 2. He never knows when Joan is going to leave or where she’s going or when she is coming back. 3. She just looks at him, a figure in the narrow hallway, dimly lit by the light coming from the bathroom. 4. Eventually, he manages to form a sentence in his head. It’s not one of those three million sentences he has been thinking about for the past few weeks, not one of those sentences that have been breeding like wine flies over an open bottle of wine. Thank you!

Is this paragraph correctly written? “I should punch you in the nose right now, you totally deserve it! Stupid.” Helen said fondly. Except she could never do that. James had such a nice little nose. That looked a bit funny when he laughed, and every once in a while you could see a smudge of ink there. Or toothpaste. Sometimes even chocolate. Oh, and that one time, a noodle (unfortunate incident involving noodle soup, a minor explosion and James foolish decision to sit within a ten feet radius from Helen and a stove).

A little help with one sentence? Quite a long sentence here, kinda artistic and I wonder if it is grammatically correct. Do you think it can be modified to sound better? :) Thanks! Lorence was at the whole other end of the spectrum; he was shy, quiet, mysterious, kind, delicate, all pale, all faded beige of the hundred million books he buried himself in, all sterling silver of scars, tarnished golds of eyes, all shades of amber and russet and auburn of tea-stains and melted chocolate, with tiny little creases in the places where he frowned and smiled and with a grin that could make the stars lightheaded.