Can these hold up a tapestry?

The specs: "Strong Grade 8 Ceramic Magnet and a 1.4" Wide Base is Capable of Holding up to 15 Lbs Under Ideal Conditions " say under ideal conditions. This means you have a FLAT iron surface to attach the magnetic clip to. So far the greatest weight I have used a single clip was 6.5 pounds. Weigh the tapestry, and divide the "load" by using 1 clip per ten pounds max. This is just in case someone pulls on it. How to get that "iron plate" on the wall, I use what is called " Large Fender Washers" - go to an auto store for them or search Amazon - make sure they are the "magnetic" variety. I glued (epoxy) the washers to the surface

Are these black or silver in color?

the steel is coated silver color. the magnet is black but you won't see it when it is sucked onto a magnetic board.

Can this hold 8mm thickness light weighted notepad?

I was able to get the clip around a spiral notebook that is a little over 1cm thick. To hold the weight, however, I had to use two clips. It sounds like what you have is lighter, though. These are strong magnets.