Fellow thieves, share your tips?

So, I've successfully robbed two out of three big shops in Rattay (the tailor and the weaponsmith). However, the armorsmith is giving me trouble. I've managed to get into his storeroom (around back and up the stairs from the shop entrance) and rob one of 3 chests there. When I return for the rest, though, the guards somehow know I'm there and always find me in the dark. Is it the noise? Do they have a sixth sense or something?

Also, some useful tips - when you're overburdened, just sneak, it's faster than walking - you can sneak back to the mill and your stash reasonably quickly. If you steal some gear and keep it equipped, it becomes "yours" after some time, i.e. it's not flagged as stolen anymore. If the guards stop you and want to search you, you can bribe them and they'll let you go, but you can also drop all the stolen shit at your feet, let them search you and then pick it back up.

Also if someone knows how often do the traders restock money, that would be awesome to know.