For the displays, as stated on the
DLC-247 page any common anode display will work.
The Symprojects shop sells an 0.8"(20mm) and a 1.5"(38mm) display which are relatively close to the 25mm(1") you're looking for.
The ones sold in the shop come on a handy breakout board with a pin header so you can just plug them in and go.
If you get a display from a distributor(like mauser or digikey) you'll have the solder on some wires to be able to connect it to the DLC-247.
You might be able to find a broken out display on ebay or sites like adafruit and sparkfun, though if you get one with multiple digits you'd have to make sure the multiplexing is the same as the "official" Symprojects modules, I.E. segments connected together with a separate anode pin for each digit.