Hi, is it possible to leave my luggage for few hours at the airport? Is there a baggage depot? And if there is ,where is it located?

No. Due to TSA Security measures. Only for deposit for 'lost and found' passengers's luggages.

Only if you're flying continental apparently, here you go from Google... Newark Airport Baggage Storage is only available for Continental Airlines passengers, and a Continental ticket and ID are required when using the NBS Storage service. Pricing: $16 perbag for bags over 60 lbs.; $10 per bagfor the first bag under 60 lbs.; $5 for each additional bag under 60 lbs.

No

Ok

No they will confiscate ir if you leave it there