Regarding chametz and utensils, how does a food utensil or any utensil for that matter, acquire a chametz status? For example, if I received a dish with mishloach manos and there were crumbs etc., does the dish become chametz? What if a cup was used for cold beer?
Also, is one required to remove food stains from clothing or upholstery?
Thank you very much.
The general principle is that anything that cami in contact with hot chametz, absorbs chametz flavor and obtains chametz status. If it was only used with cold or warm chametz this does not give it chametz status and it may be washed out and used on Pesach. A cup for beer may be an exception, as any cup or utensil that held chametz liquid for 24 hours also obtains chametz status.
Clothing should be washed, and upholstery need only be wiped down with a cloth, permanent stains do not need to be removed.
See Rama O:C 451:26, Mishan Brura ibid. 155, see here for an extensive discussion of the laws of kashering for Pesach.