Lucifer
The trolleys in economy are referred to as 'carts' and trollies of the folding type used in first and business. The economy carts are same width on 320,330 and 340 and also used on 767. There are full sized and half size. Can't tell you dimensions now but same width as meal tray and fit 24 full size trays or 42 of the 2/3 size trays.
Some airlines have regulations where one person pulling a bar must be half size or two on a full size cart - other airlines don't bother - they are very heavy!
Size of aisle depends on seating configuation and aircraft type. Most size people can slip past a cart on 767, 320 or 340 but no way on a 330 aisle is too narrow.
Suggestions for improvement:
Wheels should be designed in some material that does not snag on carpets etc and stronger - one the wheels get bent the trolley doubles in weight and impossible to manoeuvre.
Need to be made in tamper proof manner. New trolleys have grills at the back which slot into chiller blowers on aircraft to keep food cold but cannot be used for bars because catering staff rip of the grills and pinch the booze and duty free.
London bond staff have also succeeded in smashing holes in the top of carts to steal duty free items - cunningly disguised with big pieces of paper on top to cover the hole.
Hope this helps a bit!