Materials (including some non-metals) that are strongly attracted to magnets are known as ferromagnetic. If you Google for this, or just search this site, you'll find lots of articles on this subject, thoughly surprisingly I don't think the question how does ferromagnetism arise has been asked before.
Electrons have a magnetic moment so they interact with magnets. However in most solids the electrons tend to line up in pairs so their magnetic moments cancel out. This means the solid has no net magnetic moment and doesn't interact strongly with magnets. However, in a small number of solids the outermost electrons of the atoms line up parallel with each other and their magnetic moments reinforce each other to give the solid a large net magnetic moment. These solids interact strongly with magnets, and we call them ferromagnetic.
Only solids having unpaired electrons can be ferromagnetic, but only a small fraction of these solids are actually ferromagnetic. For example iron is ferromagnetic but manganese isn't, even though both metals contain unpaired electrons. Whether a solid will be ferromagnetic is exceedingly hard to predict because it is controlled by a fine balance between forces in the solid. The Wikipedia articles on ferromagnetism and the exchange interaction go into some details, but be warned that this is a complex area for the non-physicist.
There is a list of known ferromagnetic materials here.
As Hasan mentioned in a comment all solids interact with magnetic fields to some extent. Non-ferromagnets may be diamagnetic or paramagnetic. However these interactions are several orders of magnitude weaker than ferromagnetism and the interaction is too weak to be measured outside a laboratory.
Your book is wrong (or at least, overly general). Non-monotonic behaviors (i.e., increases and decreases) are seen with temperature changes for the thermal conductivity of even pure metals. See, for example, slide 20 here:
Totton's Steel Heat Treatment Handbook reports that the thermal conductivity "decreases with increasing temperature for pure iron, plain carbon steels, and low-alloy steels", whereas it increases for "high-alloy steels such as ferritic and martensitic steels":
Looking at it from the other direction, consider a metal with a strong negative temperature coefficient of thermal expansion, say, tungsten. The addition of a few impurity atoms technically forms an alloy, but I wouldn't expect any dramatic changes in thermal conductivity. So the book's blanket statement is much too general.
What your book may be trying to say is that in pure metals, thermal energy is often transferred primarily by electrons (as opposed to phonons). As the temperature increases, these electrons tend to be more easily scattered, thus suppressing that mode. This mechanism would explain the often-seen negative temperature coefficient for thermal conductivity in pure metals.
But the electronic thermal conductivity is also suppressed by increasing solute concentration in alloys, also attributed to scattering. (The lattice thermal conductivity, which is mediated by phonons, is typically also suppressed but to a lesser degree.) As a result, lattice thermal conductivity may become the dominant effect, and this mode exhibits a strong positive temperature coefficient because phonons are thermally excited.
The temperature dependence of thermal conductivity also depends on the forming method (which alters the grain size, for example) and on impurities, among other factors. Although certain trends can be reasonably explained, it's not an area in which you can expect broad statements comparing pure metals to alloys to hold across a variety of conditions.
Best Answer
It's true they are not common, but there are other alloys that use carbon. Nickel is probably one of the more common metals that form alloys with carbon that have desirable properties. For example, Nickel 200, Nickel 201, and Nickel 205 all contain carbon. (See: http://www.asminternational.org/documents/10192/1852239/ACFA9D7.pdf/d490dee6-620e-4e38-b64d-53dd02c5fc81). Chromium and Tungsten also form alloys with carbon called Stellite Alloys: See http://en.wikipedia.org/wiki/Stellite (although some, but not all, stellite alloys contain iron too).