The system will only hold a maximum of 3 wonder cards. You might want to use it as much as possible before deleting it, though. Pokemon Diamond and Pearl also hold a maximum of 3 wonder cards, too.
No
heartgold and soulsilver
You can transfer Pokemon, but you can't trade. Since HeartGold was released before Black, HeartGold doesn't know Black exists. However, Black knows HeartGold exists. You need to be on Route 16 in Black version, which requires beating the Elite Four.
In HeartGold, Lance is the champion, so you'll have to defeat the Elite Four before you can battle him.
Yes you can.
You have a Pokemon hold them and then clone the Pokemon. (Put the Pokemon in the PokeWalker and turn the DS off before it saves)
yes
no you will get a ho-oh figure with the game
no
Your game, Pokemon HeartGold, might not play on your 3DS and DS Lite when the game was playable before because you have damaged the disk or cartridge.
preordering is buying something before it's released and they mail it to you on or after the releasedate...To preorder Pokemon heartgold and/or soulsilver go to http://www.play-asia.com/
You cannot transfer pokemon from HeartGold to Black until after you finish the main part of Black. Do note that you will be transferring pokemon from HeartGold to Black, not trading pokemon between the games.