Fasting as long as possible if you find that at a certain point your bg flatten out the clearer picture you've got the better it is, if you've feel peckish then Sugar free jelly helps starve off the hanger pangs.
As to the set you could try an angled version.. and/or perhaps have a go at self insertion
Most common things for causing kinking issues is either the force of the inserter and/or the cannula is hitting the muscle underneath...
I use a angle cannula which I self insert and in 4 years I've had one set kink on me and I can't be sure whether I kinked it when taking it out, as I hadn't experienced any problems it was just kinked when I checked it after I removed it..
Some people find that when they change their sets they can get a rise in BG just after, a lot find leaving in the old set in for a couple of hours helps to prevent this from happening, some bolus an extra bit of insulin...
Tip here double check the booklet that comes with your sets to insure that when you are priming the cannula that you are priming by the correct amount, as my rep told me the wrong prime for my set I was told 0.5 but when I checked the booklet it's actually 0.7u for the prime