1: No, its often spam and unlikely to find you a buyer.
2: No, you don't need to send 10 requests. Only ever respond to a request if it is something you can accomplish, with an appropriate time and budget requirement for your work. Taking on orders that you are not qualified for is not helpful. It will leave the seller stressed and the buyer unhappy.
3: Nope, whilst you can learn a lot from the forum, being active here makes NO difference to your orders. You won't get orders by commenting on every post on the forum. Most people on the forum are sellers and even if there was a buyer looking through the forum, it is unlikely they would be convinced to buy a gig from somebody who spams a forum. Also I have seen 0 evidence that being online constantly on Fiverr itself is useful for getting more sales. Just go online when you are working or check occasionally throughout the day.
4: The only correct advice here in that of course you should always strive to improve. But even that isn't a requirement for getting your first order.