Shuttle xpc SB86i Questions

I just bought a Shuttle xpc SB86i barebones kit, and I've got a couple
of questions. I've been building PC's for myself and family and
friends for over 10 years, but this is my first SFF system.

Included with the system was a rectangular metal plate, about
3"x2"x1/4". It appears to be aluminum sandwiched between two
beige-colored layers of some other material, that are protected by
sheets of plastic film. It's fairly heavy, so it might not be
aluminum. There's no mention of it anywhere in the manual, including
the parts list, and I can't figure out what it's for. No system I've
built has ever used anything like it.

Second question: I noticed that the "load plate" that holds the CPU in
place had a slight upward bend instead of being flat. Is this normal,
or had the part in my system gotten bent somehow? After seating the
CPU, I was able to lock it down with the socket lever, but I was a
little concerned that it might crack something. My last several
systems have used AMD CPU's, so I don't know if this is normal for
current Intel CPU sockets.

I'm building this system for my parents, so it needs to be as
trouble-free as possible. Any help with these issues is appreciated.