It's been a while since i played On, so i can't answer all your questions, but i can do a couple.
2. Papyrus, pottery and maybe bricks would be my choices off the top of my head.
4. Absolutely. Unrestrained Hippos "love" to eat reed gatherers. A couple manned towers will keep your papyrus production going.
5. The game request does come very early. Maybe just a small settlement (one or two houses), with the storage yard and the hunting lodges. Of course, if you want to feed your people that game meat you'll have to man the ferry on both sides to transport it.
If you decide to do a search of the Game Help forums, besides On, you might look for Onions (the wonderful people of On) [This message has been edited by homegrown (edited 09-11-2000).]