General question: Is it correct that there are no points awarded for figuring out only the numbers that correspond to the smurfs (Part 2), to the dwarfs (Part 3), to the muppets (Part 4)...?

That is correct. Points are awarded only for correctly solved sudokus.

Part 2: Is it necessary for solving to know that different smurfs denote different numbers? In other words: Is it possible that one triple of puzzles is solvable with two different numbers (say 35 and 36) and only gets unique because one of the both numbers (say 36) is used by a different smurf? In this round this could be very inconvenient because there are lots of puzzles (30). If not all triples can be solved independently this could become very confusing (and the order you tackle the puzzles could become important).

You're right in everything you wrote.

Part 4: Just to make sure: All 15 puzzles in part 4 use the same set of 9 muppets, i.e. each of the 9 muppets is synonymous to a different digit and this digit is the same over all 15 puzzles.

Again, you got it right.

Part 5, Puzzle 7 (Kendoku): Is it possible that the cages with subtraction and division are larger than 2 cells? I.e. the clue "2-" could take a "295" in a 3-cell cage?

All cages with subtraction and division in the actual puzzle are two-cell cages.

Part 5, Puzzle 8 (Product squares): Are all 2x2 squares marked gray that fulfill the multiplication property (doesn't make much difference, actually)?

That is not known. Maybe, and maybe not (but I agree that it doesn't make much difference).

Part 6, Puzzle 12 (Winnie-The-Pooh): Some specific language (probably different from the example in the booklet) will be used. Will it also have characters with accents or some other special characters? In the example the number six contained a S with an accent. But in the puzzle a given S could denote either a "normal S" or a "S with an accent" (in the middle 3x3 cage). So it was allowed to add an accent to any given letter S. Will that be the same with the competition puzzle?

If the letters in the actual puzzle include diacritical marks (eg. š, č, ž and ć in Croatian) then they have to be respected. What I mean is that if you find an S in a cell then the number you write in has to contain letter S and it cannot be transformed into Š. If you find Š then you have to write a number with a letter Š.

In the example the three cells with letters S in the central box contain three numbers with a letter S (7-Sedam, 8-oSam and 6-šeSt).

Part 8: Is the following correct (as far as you are allowed/willing to answer): This round will be a manipulative round with a big diamond-like board. Additionally to this board we are given 12+1 sudoku puzzles where some clues are given (also on the 13th puzzle?). The sizes of the sudokus will exactly fit the big board so that we can lay them on the board.

*) Is it necessary to solve the sudokus on the seperate sheets or on the big board or is both accepted?

*) Is it allowed that there are given clues in the overlapping areas (gray on the big board)? Is it allowed that two puzzles that overlap both have givens in the overlapping area (different numbers in different spots of course)? Is it allowed that two puzzles that overlap both have the same given clue in the overlapping area (same number on the same spot of course)?

*) When using the three 3x3 central pieces to solve the 13th puzzle: Is it allowed to place the 3x3 pieces over given numbers of the 13th sudoku (as long as they are identical of course)? Or do the 3x3 central pieces have to be placed only on EMPTY 3x3 boxes of the 13th puzzle?

First of all, to disappoint you - there is no big board, sorry if the instruction misled you to believe so.

There is only a scheme, printed on an A4 paper and also included in the puzzle booklet, according to which you have to arrange the twelve sudokus. The scheme is already given to you in the instruction booklet, so you know already what to do.

I am allowed to tell you that all puzzles have multiple solutions if you solve them independently, but only one solution when you correctly arrange them according to the scheme.

Each puzzle is on a separate piece of paper, and each team will have a bigger table, so you'll have enough space to combine and connect the sudokus.

Two sudokus overlap by their corner 3x3 boxes.

All overlappings of given numbers are allowed, between any two sudokus 1-12, and also between the givens in the central boxes of the corner sudokus and the givens in the 13th puzzle (the boxes in the 13th sudoku do not need to be empty to have a box from previous puzzles placed into them).

And very important: when we say a BOX - we mean a 3x3 square with a thick boundary, you got that correct also.