Traffic circles (or “roundabout” for you blowhards out there) are a 1-way road that you enter by yielding. Everybody coming up from slightly behind your left shoulder has the right of way, you may enter when it’s clear. It’s not necessary to signal upon entry, since the road is ONE WAY, nobody thinks you’re going any other direction. When you approach your exit, go ahead and signal that you’re leaving so the people trying to enter at that spot stand a better chance. You don’t stop in the middle of the traffic circle, that’s dangerous. You don’t expect others to stop in the traffic circle, that’s dangerous. If you city has installed a mini traffic circle at what should be a 4-way stop, then yield to the person on your left and elect new city officials because those guys suck.
When your lane on a multi-lane road ends, travel to the END OF THE LAND, then zipper into the other lane in an orderly fashion. Don’t panic and stop in the middle of your lane with 100 feet ahead of you, frantically blinkering and trying to nose into traffic, thereby creating a long line of pissed off people both in your own lane and the next. Just go all the way to the end and watch the car ahead of you proceed to safely change lanes, then wait for one car in the oncoming lane to go, then the next one waits for you. They won’t always, but don’t presume dickishness. Don’t be a dick either, by forcing your way into a spot that wasn’t meant for you. When it’s your turn to let someone else in, go ahead and DO THAT so as not to encourage people to muscle in when it’s not their turn. It’s much like kindergarten, in that respect.
Contrary to traffic circles and merging traffic, four-way stops progress in a right hand direction. When any number of people greater than one approach an intersection at the same time, look to your right. Nobody there? Congratulations! You get to go first, next, etc. Failing to stop gets you de facto right of way status, and also the title of Grand Dickhead, or “Asshole” for short.
Inclement weather creates hazardous road conditions. There is no immunity to these conditions based on the price of your car. An $80k vehicle slides on the ice in the same manner as a $10k vehicle, and crunches just as dreadfully. It does, however, provide a very satisfying spectacle to everyone who doesn’t drive an $80k vehicle to see it crunched on the side of the road, so if that’s a public entertainment you want to provide, then by all means, don’t slow down on wet or frozen roads.