Oh, and since I am in the middle of doing this, I can also give you the pitch. It is 2mm. IOW if you turn the bolt one turn, it moves 2mm in the thread, up or down.
If you don't have a thread gauge, use your vernier, measure out 10mm, and count the number of tops of the thread contained in the 10 mm measure, when you place the jaws along the length of the bolt.
You will see that it is 5. Thus 10/5 = 2mm.
And for the second question, - if there is space for a bigger head -, not really. Space is very confined, and adding a bigger head is like inviting extra trouble.
just re-use these bolts!!!
