they will make your feet tired, because your feet are working in a different position now.
Pressure/pain in the arch near the heel is exactly where you will feel it if you have been overpronating and now you're being corrected by the insole. The ramp up to the arch in the insole acts like a kickstand at the sustentaculum tali of the calcaneus, and keeps your foot from collapsing.
Foot exercises will strengthen you and allow your own muscles to hold you up instead of needing a kickstand.
If the insoles get irritating, take them out and give your feet a break. 12 hours on your feet on the first day is pretty hefty.
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson