ackies dig, it's not from insecurity, it's just what they do,
they like to explore thier surroundings, they are very inquisitive,
but at the same time, they like places to hide when they need to, so cage furniture they can climb on, through, under is great. make sure if they can get under it, that it cant sink and trap them.
chicken mince is not reccomended, if left alone it can go off to quick.
best to use kangaroo mince, you can buy it as cat food from woolies and aldi.
66 is a good temp, but they really do like it hot, so don't be afraid if it gets to 70-75,
mine has gone over 80 before, but only on the basking spot, rest of thew enclosure is room temp, 25-35*
the UV tube is not nessicary, but wont hurt.
search my threads and you'll find alot of usefull info.