Synthetic bags are more functional when wet, but the bulk and weight is like ridiculous compared to down. For that reason I've not used one in years. Semi waterproofed down bag seems like a good idea, but even regular ones are fine if you're careful. I've camped more nights than I remember in the rain using a down bag without getting it wet.

If you actually expect rain, just about any tent is going to be infinitely less miserable than sleeping in a bear burrito bag. Also, if you get a down bag (which you should) the condensation may well render it useless.

2p as has been pointed out are not much heavier and give you some extra space to keep your bags out of the rain. 1p is still way better than bivy.

The Marmot tents REI sells are a good deal and come with a footprint.