<image>During a comprehensive quality test, there are a total of $$40$$ examination rooms, with $$30$$ candidates in each room. After the test, to investigate the correlation between their pre-test training and test scores, the candidates with seat number $$05$$ from each room were selected and their scores were recorded, resulting in the frequency distribution histogram shown in the image.


$$(1)$$ What sampling method was used in this survey sampling?
$$(2)$$ Estimate the number of excellent performers (those who scored $$80$$ points or above) in this test;
$$(3)$$ Provide the mode, median, and estimated average score for these $$40$$ candidates.