How bad is my hair condition?
Not bad. In my opinion, you are definitely losing hair, though it is difficult to say how quickly it will progress. Considering that you are 19 I'm guessing it is aggressive-ish, but some people's hairlines 'mature' aka recede and thin very slowly. Your temples are clearly thinning, although it is difficult to say the speed at which they will recede. Do you have pictures of your hairline from when you were say, 18, 17, 16? Does your father have his hair? How about your uncles and grandfather on your mother's side?
Your crown area does look a little concerning, although it is difficult to say considering that is where your hair whorl is located, you could just have a very prominent hair whorl. Similarly, very bright lighting tends to make things appear thinner, particularly with hair that is as long or longer than yours.
What norwood i am?
Norwood 1.5 - 2
Should I start taking finasteride at my age?
That would be a question for your doctor/dermatologist. Personally, I would not. There is still a lot of secondary sexual development going on when you are a teenager that you could inadvertently f*** up by taking finasteride at an early age. Considering that your hair loss is not excessive (ie, NW4 when you are 19), I would hold off and keep an eye on the situation. If you are very concerned about your hair I would take a series of close-up pictures of the temples with your hair pulled back, the crown and the hairline, much like the pictures you have taken already. Compare the photos that you take in a few months to the pictures now, likewise for pictures a year down the line. Make sure the lighting is consistent throughout the pictures so that you can get a clear picture of the speed at which your hair loss is progressing.
If your hair loss is clearly aggressive and you have lost a substantial amount of hair in the next 6 months, then perhaps I would reconsider my opinion on finasteride, otherwise, I would say to wait until you are at least 21 to start, to be honest.
How would you see to take 0.5mg daily?
Don't know what this means.
How much hair could I recover?
Well if you were a very good responder to finasteride, potentially all of it. This is unlikely though, as finasteride typically just slows the loss of hair down significantly, so you don't lose much hair while taking the drug. Minoxidil is used for growing hair, with it you could easily grow most of it back I would imagine, assuming you are not unlucky and respond decently to the medicine. Keep in mind that you will still lose hair with minoxidil, so it is best combined with an anti-androgen like finasteride.
You have caught your hair loss very early, which is good news and half the battle. Normally I would advise that people with any hair loss that they are concerned about to begin taking finasteride immediately, though considering your age I can't really in good conscience recommend it, who knows what long-term damage you could be doing. Keep an eye over the next 6 months - 2 years, and come back/ visit a dermatologist then. That's my 2 cents.
Best of luck bro