1) From the text:
"He was not over thirty. His eyes were very dark brown and
there was a hint of brown pigment in his eyeballs. His cheek bones were
high and wide, and strong deep lines cut down his cheeks, in curves
beside his mouth. His upper lip was long, and since his teeth protruded,
the lips stretched to cover them, for this man kept his lips closed. His
hands were hard, with broad fingers and nails as thick and ridged as
little clam shells. The space between thumb and forefinger and the hams
of his hands were shiny with callus.
The man's clothes were new—all of them, cheap and new. His gray cap
was so new that the visor was still stiff and the button still on, not
shapeless and bulged as it would be when it had served for a while all the
various purposes of a cap—carrying sack, towel, handkerchief. His suit
was of cheap gray hardcloth and so new that there were creases in the
trousers. His blue chambray shirt was stiff and smooth with filler. The
coat was too big, the trousers too short, for he was a tall man. The coat
shoulder peaks hung down on his arms, and even then the sleeves were
too short and the front of the coat flapped loosely over his stomach. He
wore a pair of new tan shoes of the kind called "army last," hob-nailed
and with half-circles like horseshoes to protect the edges of the heels
from wear. This man sat on the running board and took off his cap and
mopped his face with it. Then he put on the cap, and by pulling started
the future ruin of the visor. His feet caught his attention. He leaned
down and loosened the shoelaces, and did not tie the ends again."
2) I believe that the truck driver's habit was "chewing gum."
3) Joad is angry and embarrassed;
"I ain't keepin' quiet about it. Sure I been in McAlester. Been there four years. Sure these is the clothes they give me when I come out. I don't give a damn who knows it. An' I'm goin' to my old man's place so I don't have to lie to get a job."