OK... Angle grinder basics...
WEAR GOGGLES. ALWAYS. I MEAN... ALWAYS.
They can bite. They can really bite.
When you first switch 'em on, there can be quite a kick of torque. Be ready.
They take a little while to spin down after switching off. This is when I usually catch something I didn't intend to and didn't want to.
If you're using a cutting disc, always use the edge, not the face, and never be tempted to try to grind with it.
Cut or grind at the wrong angle, and you will get vicious kickback. Be prepared.
Don't try and "flex" a thin cutting disc. If you drop it, and you think the disc hit the ground anything more than trivially, bin the disc. You REALLY don't want bits of disc flying around.
If you've been cutting bolts or anything particularly solid and metal, the piece WILL be hot. Hotter than you think. For longer than you think. Much hotter and longer... Don't pick it up.
Others can probably fill in the gaps, especially when it comes to slate - I tend to use 'em on steel.
Probably because they're not trying to cater for every language in one manual, since the branding (and manual) is UK-only...
I still wouldn't trust even the best-written manual in the world to show me how to use a potentially very dangerous power tool, though - and a good manual can lead you into a false sense of security.