When 60 < x < 80, y=-0.05x+5 (ten thousand pieces).

2) According to the first question, when x=50 yuan, 30,000 pieces can be sold every month.

Therefore, the income = 30,000 * 50 = 1.5 million, the cost = 30,000 * 40 =1.2 million, the fixed expenses = 1.5 million, and the remaining1.5 million, including profits and employee salaries. When the minimum profit is 50,000 yuan and the salary of employees is 654.38+10,000 yuan, then the number of employees =110,000 /2500 = 40.

That is, the company will arrange up to 40 people.

3) Since the fixed cost is10.5 million yuan and the wages of workers remain unchanged, let's first discuss the maximum gross profit (sales-cost) when the selling price is X yuan.

If x is within [40,60], it becomes the value of x when (-0. 1x+8)*(x-40) obtains the maximum value, and x=60 is calculated, and the gross profit at this time is 400,000;

If x is within [60,80], it becomes the value of x when (-0.05x+5)*(x-40) obtains the maximum value. Calculate x=70, and the gross profit at this time is 450,000.

Therefore, the price should be set in 70 yuan, and the profit can be maximized, with a gross profit of 450,000.

There are 80 employees in the company, with a monthly salary of 2500 * 80 = 200,000 and a fixed fee of10.5 million, so the monthly net profit is 50,000.

So the loan of 800,000 yuan can be paid off in 16 months.