mediums will work fine. if the nucs when made up have small population you may want to situate them in some partial shade since if anything they can have temperature regulation problems. if they are fat with bees this doesn't seem to be so much a concern. ideally you want the population some where in between. you have to monitor the small population ones fairly regularly to limit shb problems. feeding just a bit during the introduction stage (maybe no more than a pint or so) should get the queen off to a good start.