Gulika Kalam is the third of the three inauspicious daylight segments (with Rahu Kalam and Yamagandam), associated with Saturn's shadow influence Gulika. Some traditions weigh it in Muhurtham selection alongside the other two.
Gulika Kalam is the daily window associated with Gulika (also called Mandi), a sub-division linked to Saturn. It is the third of the three inauspicious periods read from the weekday, with Rahu Kalam and Yamagandam.
The daylight span from sunrise to sunset is divided into eight equal parts, and one of those parts is assigned to it. Which part depends on the weekday, so the window moves through the day across the week.
Yes. The window is derived from local sunrise and sunset, so it shifts with both the date and the latitude/longitude of the place you enter.