Your waltz accents are incorrect. The accent should be on the first downbeat of the measure, with the other two being slightly weaker.
Regarding 3/4 and 6/8, their beat types (simple or compound) and meter types (duple, triple, quadruple) are entirely different. 3/4 is an example of simple triple meter. There are three beats per measure, each beat receives the value of a quarter note and divides equally into two eighth notes. 6/8 is an example of compound duple meter. Here we divide the beat into three equal parts, so the note value representing the beat will have to be a dotted value. This is where all the confusion takes place between the two time signatures. Simply put, compound meter tells you the number of divisions of the beat (top #) in a measure and the division of that duration (bottom #). If the number that indicates how many beats there are per measure (the top) is divisible by three, OTHER THAN THREE ITSELF, it is compound. So, 6,9, and 12. Don't worry about anything passed that because it will require a bit more explaining (I don't feel like discussing complex time signatures or borrowed division right now), so let's keep it simple (lol).
Anyway, six divided by three equals two. That means there are two beats per measure in compound duple, not three, four, or six! Next, you have to look at the number that represents the value of each beat per measure (bottom #). However, in compound time, that number is represented as the division of the actual beat note duration. Since there are two beats per measure, and the dotted quarter note gets the beat note, the division of each beat per measure is thee equal eighth notes, hence 6/8. So again, two beats per measure, dotted quarter note gets the beat note, and each dotted quarter is divided into three equal eighth notes.
That's quite different than 3/4 (simple triple).
I think this is enough for now because this was suppose to be a pretty basic explanation in response to all the confusion thus far. An important thing to remember is that a measure of 6/8 in six does not sound like compound duple, it sounds like two measures of 3/8. In true compound duple, the listener will be able to hear two compound beats per measure, not six simple ones. The reverse is also true.
Edit: Btw, this might not matter to most of you, but I'm a performing classical guitarist and there's a certain connotation these time signatures bring to me. There's a reason why composers such as Bartok and Brouwer wrote various study's and pieces that were identical except for the time signature. There's an art to notation that is quite overlooked these days. 6/8 was there to indicated to play the piece faster than one in 6/4. Mixed meter of 2/4 + 3/4 is used to show there should be a strong accent on each downbeat so it doesn't sound like syncopation in 5/4. These are just some basic examples, the list goes on. I just wanted to point out that notation regarding time signatures isn't always arbitrary. Cheers!
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