Question: I have some basic questions about my 1-year-old pug. 

1. How much should he eat? Typically he should eat 2 times, but he always keeps some food in his bowl and whenever he wants he eats. Is this a good practice? (I use Royal Canin Mini Adult)
2. Now-a-days he always wants what I'm eating. How to stop this?

I'm too new (being my first pet) in this area, so your views are appreciated.

Answer: 
1. As Gone2 has stated, you should definitely regulate your pug's intake by removing the food after 15-20 minutes with each feeding.
All kibble has feeding directions on the back, so you should follow the feeding recommendations on the bag for his weight unless otherwise directed by a veterinarian. Dogs should generally have a thin layer over their midsection but not so thick you can't feel their ribs. The ribs also shouldn't be visible while they're relaxed.
2. For begging, you can try redirecting by rewarding him when he doesn't beg. Or teach him a down stay. Another method is to give him a toy, himalayan chew, or bully stick to work on while you eat in peace.
1. Leaving food out beyond the two set feeding times is not a good practice. You should go by the recommended amount on the bag for his weight and split that in half; one portion each feeding.
2. To prevent begging you should avoid reacting to the begging and if necessary physically separate yourself from the him while you are eating as most of what we consume can be extremely unhealthy for a dog to consume (salts, sugars, and artificial byproducts they aren't meant to have).

Lastly, have you looked into raw feeding?