(1) According to the measurement, the distance from Bookstore to Hongxing Primary School is 1.2 cm.

Because 300 meters equals 30,000 centimeters,

Then the scale of this graph is1.2: 30000 =1:25000;

(2) The distance from Hongxing Primary School to the cinema is1.6cm..

The actual distance is1.6× 25000 = 40000 (cm) = 400 (m);

400÷50=8 (points);

(3) Because 500 meters =50000 centimeters,

The distance from Children's Palace to Hongxing Primary School is 50000×125000 = 2 (cm);

As shown in the picture, it is the location of the Children's Palace:

;

(4) The distance from the department store to Hongxing Primary School is 1 cm.

The actual distance from the department store to Hongxing Primary School is 1×25000=25000 (cm) =250 (m).

400+250=650 (meters);

So the answer is: (1) 1.2 cm,1:25000; (2) 1.6 cm, 400 m, 8; (4) Xiaoxiao walked 650 meters to the cinema after coming out of the mall.