Not sure how this is handled in Domoticz. On my controller (FHEM) you can also use the "by-id"-path of the serial gateway (or alternatively the "by-path"-path) to make sure you get the rigth data from the right point in system. For getting the necessary info, you type "ls -l /dev/serial/by-id" (linux-console) and most likely you have to enter the entire path for defining your gateway correctly in Domoticz, eg. "/dev/serial/by-id/usb-FTDI_FT232R_USB_UART_A901RQ9F-if00-port0" (add the baud rate, if necessary).

Dallas sensors are good. Well for incubator DHT22 should be fine, I just don't like DHT because they tend to jump values around, but yes a secondary monitor is nice to prevent roasted chicks :D