I'm assuming this is a legitimate thread, and not some taunt from laughingman

...
(1.) Awful idea - just don't. Automated Workers don't understand city specialisation. They don't understand your strategy and goals. They don't respond to the changing dynamics of the game. They don't anticipate your civic shifts. etc. etc.
One of the keys to Civ4 imho is to specialise your cities - if your city is clearly going to be used as a unit pump - don't let automated Workers go and build Windmills on your Hills and Cottages on your Grassland, where your emphasis for that city is

and

... not

- and otherwise for science centres and

farms which have their own needs on

and

respectively.
Automated Workers aren't bad at building lots of hybrid cities, but no good at focusing your cities' purposes.
From time to time they may weaken your empire - such as building a Plantation over a Town on a resource where you've got multiples.
(2.) You need to consider the food needs of your city so it can grow appropriately (food count), its longer-term role as a specialist city in the broader empire, your immediate needs, and then direct your Workers to strengthen your empire by building appropriate improvements.