What does the dots above the repeated notes in measure 1 mean?
A dot above or below a note means playing Staccato, a way to accentuate the note by suddenly stopping it's articulation, so that it is much shorter than regular notes that are usually bound to another in a way that the sound does not stop in between them (Legato).It is not meant to affect the Tempo or the Volume, i.e. it is not slower, faster, louder, softer -- just play each Staccato note much shorter, to separate it from the others.If you want to read an excellent reference article about Music Notation in general, look into the corresponding German Wikipedia entry "Notation (Musik)". «Staccato» is explained there as no. 10 in the «practical example» chapter, using the "Donauwalzer" (Donau Waltz).Or else, directly read the English Wikipedia entry about Staccato, since this (and many other subjects) is not even mentioned in the Wikipedia entry about Musical notation...