Hi there! You add the dice together only when performing actions. The city table is a d66 table that should be rolled on separately - you do not add the dice together for this, but read them as they land. For example if you roll a 3 and a 5 then you would have 35 (if you look down the number column you'll see it goes 11-16, 21-26, etc. which are the only combinations that can be achieved by reading the dice as a 2 digit number). You can roll once and take a whole row together or roll for each column to get more varied results.
Threats appear as part of the Sate Your Hunger action (which you need to do every day).
There are 3 approaches on your character sheet - Violent, Beguiling & Stealthy. You choose which approach to use for the action you are taking, if it doesn't mention one specifically. For example if you Take a Risk, you could be smashing through a window (Violent) or trying to talk your way out of something (Beguiling).
Hope this helps!