I have learned over the past 60-some years to take my sleeping bag with me when I turn over, which I do a lot. I therefore avoid sleeping bags with less insulation on the bottom, those with a pad pocket instead of insulation on the bottom (the pad would end up on top), quilts, etc. I would like to have side baffles, because every evening I have to fuss with my bag to get the down evenly distributed on top and bottom, and it's a pain. And yes, the down does loft up again when the spot you've lain on ends up on top.

You don't need to worry about condensation inside your bag unless it's below freezing. Above freezing, the heat from your body pushes the moisture coming from your body through the insulation and through the outer shell of your sleeping bag into the tent. That's why the outer shell needs to be breathable. Below freezing, though, the moisture from your body tends to condense when it hits the colder (in those temps) outer shell of your sleeping bag, thus dampening the down. I experienced this during my recent trips to the Rockies. It's therefore helpful to have some kind of vapor barrier liner inside your bag on below-freezing nights, especially if you're out for several nights in a row and will not be able to air out your bag. The vapor barrier is actually quite comfortable in low temperatures and even adds a little warmth to your bag.