The Panchang is the Vedic almanac for a single day. Panchang means five limbs, and those five — tithi, vara, nakshatra, yoga and karana — are what it lists, together with sunrise, sunset, and the inauspicious windows worth working around.
Today’s Panchang is calculated for your location, because almost everything in it is measured from local sunrise rather than the clock.
Rahu Kaal is a stretch of roughly ninety minutes each day traditionally avoided for beginning anything of consequence. It falls at a different point on each weekday and is calculated from local sunrise and sunset, so it shifts through the year and differs between cities. Yamaganda and Gulika Kaal work the same way and are treated similarly. None of these are held to spoil work already under way — the caution is specifically about starting something new.
If you compare sources you will find they rarely match exactly, and the reasons are legitimate. Panchang is local, so sunrise and sunset move the whole day’s timings by city. Traditions also differ on the ayanamsa value used to convert to sidereal positions, and on whether the day begins at sunrise or at midnight. Neither is wrong; they are different conventions, and it is worth staying with one source rather than averaging several.
It describes the day, not you. Everyone in the same city shares the same Panchang. How a given day actually lands for you depends on your own chart and the period you are running — which is why a day marked broadly auspicious can still be an awkward one personally, and the reverse.
Tithi (the lunar day), Vara (the weekday), Nakshatra (the Moon’s lunar mansion), Yoga (a combined Sun–Moon calculation) and Karana (half a tithi). Panchang literally means five limbs, and those five are what it lists.
A roughly ninety-minute window each day traditionally avoided for beginning anything important. It falls at a different time each weekday and depends on your local sunrise and sunset, which is why a Panchang without a location is not much use to you.
Two reasons. Panchang is local — sunrise and sunset shift the whole day’s timings by city. And different traditions use different ayanamsa values and different day-start conventions, sunrise-to-sunrise rather than midnight-to-midnight.
A lunar day: the time the Moon takes to gain twelve degrees on the Sun. A tithi is not twenty-four hours — it runs between about nineteen and twenty-six hours, so it can begin and end at any clock time and occasionally skip a day entirely.
No. The Panchang is the same for everyone in a given place on a given day. Your chart decides how a day interacts with you personally; the Panchang describes the day itself.