Standard seems to be 3000 mg (3 grams) a dose. If your 150 to 200 pounds usual suggestion is 2 times a day. If 200+ then 3 times a day.
Most common use is pre-work out. Normal suggestions for pre-work out are 3 to 9 grams. If I am mixing my own cocktail for pre-workout I go with 6 grams personally.
Most Arginine products recommend not taking it for more than 12 weeks, then at least 4 weeks off. This is so your body can balance itself out and not become dependant on the high doses of arginine you are giving it.
Studies have shown that it increases fat loss. Bodybuilding products include it to increase the “pump” you get in the gym, increase nutrient delivery to muscles, and boost natural GH levels.
List of benefits taken from wikipedia:
"Arginine plays an important role in cell division, the healing of wounds, removing ammonia from the body, immune function, and the release of hormones."
"The benefits and functions attributed to oral ingestion of L-arginine include:"
"Precursor for the synthesis of nitric oxide (NO)
Stimulation of the release of growth hormone.
Improves immune function
Reduces healing time of injuries (particularly bone)
Quickens repair time of damaged tissue
Reduces risk of heart disease
Increases muscle mass
Reduces adipose tissue body fat
Helps improve insulin sensitivity
Helps decrease blood pressure
Alleviates male infertility, improving sperm production and motility
Increases circulation throughout the body, including the sex organs" -End Quote
Hope this helps answer your questions.