Well the steel used to manufacture fasteners is generally a medium carbon steel I on our bills of material we only ever specify the grade 8.8,4.6 etc so I suppose the short answer is yes.
Depends on what you mean by "load bearing capacity". The reference desertfox gave lists material requirements in tension. How are you using the bolts? Shear?
If you can explain in more detail exactly what your looking for we can give more detailed answers but your questions are so vague its down to our interpretation
Actually we have been asked to quote the pipe clamps along with the Bolts/nuts and the load has been stated in the drawing itself.,We have considered M24 instead of M25 as shown in the drawings and now the client is asking for the load capacity of these bolts.
The structural steel design code or handbook in your country should furnish the information you need about the bolt capacities. Likewise, any reputable bolt manufacturer/supplier will have the information readily available.