I guess I should clarify my intent with the items: these are things that are necessary to initiate an attack on a town, as in, withouth X# of items in your armies inventory, you don't even have the option to attack. These items would be placeholders, in that they do nothing but allow you to attack. Also, I think they should be relative to the number of troops you have, i.e. every 2 troops need 1 tent, every 500 troops need a latrine, etc... This would make the cost of large armies scale up quickly, as they would do historically.
Also, I suggest a minimum wait time of 48 hours before a siege can be fought. I would be happy with longer times as well, possibly depending on the size of the city (maybe by population?) This is to allow time for the army to fully invest the town, i.e. dig ditches, build fences, set up a fortified camp, etc... Also, in terms of the game, it would allow relieving armies to have a chance to join the battle. This was also often the case historically.
I know not everyone is into the realism thing, but in my opinion it would add a layer of immersion to the game and also make large battles more strategic. If a castle can be relieved by an army that's over 24 hours travel time away, you need to pick your strikes or use deception or multiple strikes to achieve your goals. I just think it would make things more difficult, and thus, more interesting.