1.What does here timetable / schedule mean?
Let's take the sentence
The sun rises at 6.00 tomorrow.
Timetable means that you personally played no part in causing the sun to rise at 6.00 tomorrow. The sun follows the laws of nature, like a train following a timetable. It will likely follow the same laws for a long time yet, and have been following them for a long time.
Imagine a person saying to his friend:
The train to Yuma stops in our town at 3:10 tomorrow.
The person is not the owner of the train company and he has not decided the time of the arrival of the train. He had consulted the timetable on the wall, a timetable probably hanging there for months or years.
Let's now look at
The sun is rising at 6.00 tomorrow
The sentence is not very natural. Looking up "the sun is rising at * tomorrow" on Google brings up only 34 results, all seemingly related to the discussion of tenses in English.
The Present Progressive is used to refer to future events that have some "present reality". We usually employ this tense in discussing our personal plans.
Imagine I've just decided to wake up at 6:00 tomorrow:
Off with this laziness of mine! I'm rising at 6:00 tomorrow.
So, in a fantasy novel some wizard might say:
(wizard) Thanks to my magic, the sun is rising at 6:00 tomorrow!
(wizard's apprentice) But this time of the year, the sun rises at 7:00!
(wizard) See how powerful my magic is - tomorrow, the sun is rising a whole hour ahead of its usual schedule/timetable!
Reference: Michael Swan, Practical English Usage, Unit 214: "Future(4): Present Progressive"