Vendricce is a port city, surrounded by, and likely spotted with, lush forest. The city is extremely wealthy from taxes for goods coming in from and going out to Elfaivar. The city has been razed at least once, half a millennia ago, by the eladrin. Describing it, I would focus on the decadence of the clergy and the extreme and obvious wealth of the city, maybe noting that most of the buildings are newer than you might see elsewhere in Crisillyir. Due to its wealth, the party should be able to find just about anything they can afford to purchase. Probably less tech and more magic. Maybe if they're hard up for cash, a local RHC contact can put them in touch with a shady dockmaster looking for someone to collect on unpaid tariffs.
As far as the fair lady Ashima Shimtu goes, I would assume her motives and nature are impossible to divine for PCs at this level. Between her own power, as drained and weak as they may be, and the inherent power of a holy place like the Crypta Hereticarum, whatever magics the PCs are trying to use here probably aren't going to be strong enough to give them anything. But don't worry, she shows up later, and they can learn everything they want then. For now, it's best to keep her as mysterious as you can, I'd think.
