1. Maybe?

2. No, you can only say for sure that it is between 495k and 586k

3. No

Example:

January: 100k, 100k, 100k, 100k, 500k

Median 100k

February: 100k

Median 100k

March: 500k, 500k

Median 500k

January+March: 4x 100k, 3x 500k

Median 100k

February+March: 1x 100k, 2x 500k

Median 500k

At best, you can make approximations