Hi Toy4X4, welcome to the board!! With regard to your first question, if you are using natural (lump) charcoal, then yes you can just throw it on your existing fire. If you are using briquettes, then you should start them in a seperate location and get them to burn down to grey before adding. You will have to anticipate when you will need them, because you don't want your grill todrop more than a few degrees before adding because it will take some time to come back up to temp. With regards to the wood issue- less is more to start. You can easily overwelm the food you are cooking with too much smoke, so go slow at first until you get the hang of it. I usually use one fist size chunk on a 22.5 inch Weber Kettle to cook chicken parts or steak.
Cheers!
No, it ain't burnt- it's barbecue