If you want extended burn times look up "minion method". It's a way of getting good long burns out of a load of coals. Another option is to bank the coals from the chimney when about half the chimney is lit, don't wait until the whole thing is ablaze. That way you can start with a lower temp and close down your bottom vents as you reach your desired temp. Learn direct, indirect, two zone, three zone, and what the three second hand test is and you'll be off to a good start.
And if you don't want to ruin dinner when learning to cook on the kettle then my advice is to not walk away from it at any time while grilling or you will burn everything and keep an eye on your temps. Drop a thermo down one of the top vents like I do. There is an art to cooking with live fire that you'll get the hang of with enough practice. Good luck and congrats on the Weber!