> - Once sailing, find the wind angle. You cannot sail within 45 degrees of the wind. So if wind is coming from, say, 140 degrees, do not set your course between 95-185 or you will come to a stop. (Because physics.)
> - Sailboats are fastest when sailing 90 degrees to the wind. So if wind is 140, the fastest course would be 70 or 230. Just keep in mind that might not be the direction you need to go.
Sorry if this sounds rude, but this isn't how a sailboat works at all! I don't know enough english vocabulary on that topic to provide a detailed explanation but I'll try something anyway:
First, the angle between your boat and the real wind isn't what matters: it's the angle between relative wind and your boat that does, this angle depends on the real wind and on your speed.
The limit angle is about relative wind, not real wind, and it's not a fixed number: in depends on your vehicle (boat or other devices with sails like windsurf or iceboat) and how much “grip” it has on the water (or ice). Iceboats can have a really tiny angle for instance (few degrees).
> - More wind = faster sailing
In theory only, because at some point when wind gets stronger, you'll need to reduce your amount of sails to avoid breaking your ship. Also once again, it's the speed of the relative wind that matters, not real one, and that's how you can sail faster than real wind! (I don't know how practical this is with a boat, but with iceboats it's easy).
Sailboat dynamic isn't that hard (it's mostly basic trigonometry) but it's pretty counterintuitive. Main takeaway, sails works like wing.
Sorry for bad English.