18. (12 points) A factory produces two large products daily, with an input cost of 2000 yuan per product. The probability of a product being of first-class quality is 0.5, and the probability of it being of second-class quality is 0.4. The factory price of each first-class product is 10000 yuan, and the factory price of each second-class product is 8000 yuan. If the product quality does not meet the standards of first-class or second-class, in addition to the unrecovered cost, the production of each product will also result in a loss of 1000 yuan.
(1) Find the probability that in three consecutive days of production, exactly one day has both products of first-class quality;
(2) Given that one of the two products produced on a certain day is of first-class quality, find the probability that the other product is also of first-class quality;
(3) Find the distribution and expectation of the daily profit $\xi$ (yuan) from producing this product.