ooh which print did you get??? i have the flowerpower in easyfit and a wrap and a cherrylicious one.
you dont need to put an insert in but you can to increase the absorbancy. we have to cause my DD is a really heavy wetter. we have to double up with the BG too.
the inserts i use are bamboo ones from little lambs (i used their bamboo nappies too)
http://www.littlelamb.co.uk/itemdetl.php/itemprcd/Bamboo-Night-Time-Booster
i also user a fleece liner.
before you use them wash them once with a bit of soap/powder then keep putting them on the rinse cycle for about 3 or 4 times. (because the tots bots have a bamboo tongue they need to be washed a few times)
hth