I have non-Jewish guests fairly often (board games are a good way to spend Shabbat afternoon...). Here are some things I do:
Wine: just use mevushal. Why risk either offense or waste? Your human guests are way more important than having the nicest possible wine.
I use a "night light" in each bathroom rather than leaving the regular lights on. It's way too easy to instinctively turn the lights off when leaving the room, even if you've been told about the Shabbat/lights issue. Besides, the night light is, I think, 4 watts, versus leaving a regular light on for all of Shabbat. (I do this every week, not just when I'm having guests.)
I ask them to leave the phone in the pocket/purse/backpack/whatever so that we won't be distracted as we celebrate. A non-Jew using a cell phone doesn't put the host in a halachically problematic position; it's just a distraction. So cast the request in terms of that distraction, and if it happens, don't make a big deal out of it. (If they want to take pictures or record singing, a gentle "please don't" should suffice -- people can be reluctant to be recorded or photographed for all sorts of reasons, and people are generally aware of this fact in my experience. Your guests are, presumably, people who don't want to make their hosts uncomfortable.)
I tell them that we're not expecting food contributions, but if they want to bring something, get something labeled "pareve". If it's labeled "pareve" then it has a hechsher, after all. (I haven't had the fresh-flowers problem so haven't thought about it.)
I give them a heads-up about the ritual aspects of the meal, just so they won't be surprised and uncomfortable. I cast this as saying that we say some special prayers before and after the meal in Hebrew, we don't expect them to participate, and if they feel they should, they get full "credit" by saying "amein" so they can do that and not tackle a language they don't read.
I invite them to ask questions. This conveys that I don't mind questions and acknowledges that some things might be strange to them and that's ok.