Hi, yes, I would get a faecal check done. As far as offering UVB exposure ("real" or artificial), it`s been proven beyond a shadow of a doubt that captive Varanids (when properly supported) can live long, healthy and productive lives. Having said that, there`s no evidence to suggest UVB bulbs/tubes are harmful if used according to the manufacturers instructions (the choice is yours).
If you choose to include vertebrate prey in the diet on a regular basis, no supplementation is needed (other than offering a little extra calcium if you have a gravid female).