First post & three questions

This is my first post to this list. My name is Michael Greenlee, and I've
been working on contructed languages for a few years (I'm fifteen). I've been
lurking on the list for a while now, and I have a few questions.

1. What semivowels are there other than y and w?

2. Does anyone know of any good sources for information about different
punctuation systems? All that I've been able to find so far is some scattered
information about old English, Latin, and Greek punctuation.

3. Are there any good books about Proto-Indo-European in general (structure,
phonology, etc.)? I've found plenty on the Indo-European languages, but few
on PIE itself.