Mugla: I'm well aware of the link between New Market and Shalebridge of course. but it's fundamentally the same layout so I don't see the problem with that, the river bend itself could be shuffled down a little if need be. This was really a rough draft as far as placing the original game maps, which had a knock on effect with the district borders. So there was always a patch of Old Quarter between NewMarket and Shalebridge, because it's there on the Assassin and Keeper map.
It was an assumption earlier on that the marketplace in the Ambush map corresponded to New Market so it got placed over there, even though it never really worked out (because we know G lived in South Quarter). Then we tried to keep G's apt as close as possible to the "Home Turf" note on Assassins. But I have come to the belief that the Ambush map shows us the heart of South Quarter. "Home Turf" can refer to South Quarter in general. And Gilver can go the Crippled Burrick.
Regarding the odd shape of Old Quarter: yes it is odd However if you bear in mind that Downtowne and Stonemarket could be considered part of Old Quarter (note the smaller typeface used for these districts, as opposed to the full Quarters) then the overall shape is not so odd.
I think Hightowne is on high ground (it accounts for the bend in the river).