Kingdra in Fire Red? You'll need to beat the game, get the National Dex, and a Dragon Scale and/or someone to trade with. You can't get Gen 2/3 Pokémon in FRLG before getting the National Dex.
Eggs in Fire Red? You can't even breed in Kanto, you'll also need to wait until the post-game for that.
If you need a Kingdra in Fire Red you'll need to use cheats, wait for the post-game and trade, or play a rom hack that makes Gen 2 Pokémon available earlier.