If there's condensation on the fly, then yes. This is a disadvantage of all pitch-as-one tents. But it never seems to be much, and the inner dries very quickly. It's never been a problem for me. If it's a concern, you can always separate the inner - it only takes a minute, and can be done with the outer still up.
You definitely want to have all the ventilation going to reduce condensation. The one at the top of the door seems to be the most important, and at least one of the end vents. In really strong winds I close the one to windward, bit otherwise I keep both open.
I keep the inner and outer together all the time. Obviously, you want to hang up the tent to air after any trip.
You can use a candle lantern no problem. It helps to control condensation - well I think so, some disagree. With a Uco mini, I use a piece of wire to keep the right distance between the lantern and the fabric. Because the tent is so low you'll need to be careful not to bump it with your head.