After studying for a while, I'd like to get an idea of my level by taking the HSK test and the HSKK (the speaking exam).

I found some practice tests for HSK 4 here:
http://www.chinaeducenter.com/en/hsk/hsklevel4.php

Are there other sites with more practice tests?

Also, does anyone know where to find more information and practice materials for HSKK?

Finally, I was wondering if it is possible to take the HSK and the HSKK on the same day. The testing center I would go to is offering both exams on the same day, but I'm not sure if they're happening at the same time of day.

Thanks!

The official registration website should have some practice tests, as I ve downloaded them before. I guess it was

Www.chinesetesting.cn

As for taking the test on the same day, you'd better contact your test center as to my experience they always have different schedules every month within china mainland. I ve no experience how it goes abroad though.