[The many ways to say “and” in Japanese][1] thread showed me that ～し, ～し can be used give reasons for something.
>この部屋は綺麗し広いし間取りもいいから人気がある。<br />This room is clean, wide and also good partition, so most of the people like it.<br /><br />
>ねむいし仕事があるし (I'm sleepy, and I have work to do, and...[I really don't want to] [so I can't do what you're asking])

Seems kind of like ｘし、 ｙし　[だ]から　ｚ.

Can it be used the other way around: ｚから、 ｘし、 ｙし.　
For example, 今は休暇だから本を読んでるし、泳げるようになってるし、リラックスしてる。

And how about for just serial actions, for example in reply to something like 今日は何をしてる？

By the way, I don't remember seeing ～し in any textbooks so far, is it something you'd only use with friends?

  [1]: http://japanese.stackexchange.com/questions/474/the-many-ways-to-say-and-in-japanese