This section is meant to answer all those nagging questions you might have that didn't really fit under any of the other categories...
Is there a second quest or a secret level?
With all the items you must collect in this game, you would think there would be some kind of reward in addition to a better ending. This is, after all, a Rare game. But I'm not yet aware of any such secrets. You can be sure that if I find any, I'll post information about such a secret right here.
Is there a way to make the old Donkey Kong arcade game accessible whenever I want?
Yes. Capture six banana fairies on film, and you'll be rewarded to play four different little games from the main menu (where you choose 'adventure', 'options', and the like). One of those games is the Donkey Kong arcade game. Another is the much-loved (sarcasm) Jetpac game.
Where can I find the other members of the Kong family?
You find your friends in the first three levels. Each one is rather easily found, but I'll give directions, just the same.
He's waiting for you in Jungle Japes, atop a high ledge. Once you find him, you'll have to shoot coconut switches to open the gate that keeps him locked away. One of these switches is particularly tricky. If you aim at it from across the water, you're not likely to hit it. Instead, go to the ledge slightly above and to the left of the switch, then shoot down towards the switch. The other ones shouldn't give you any problem.
This little monkey is in the Angry Aztec stage. You have to use Diddy to find her. Enter the temple and activate a switch that reveals several ledges. Hop quickly up the ledges, then you'll see a switch in the distance. If you shoot it with your peanut gun, a bridge temporarily appears. Run over it before it disappears and play your guitar on the pad. This will have a melting effect on the icy pond below. Now swim through the pond and you'll find yourself in a square chamber. Use the Chimpy charge to hit the letter switches. You should hit them in the order that spells 'KONG'.
He's easier to find than Tiny, and is also in the Angry Aztec stage. Using Donkey Kong, complete the barrel blast bonus stage. This will free a llama from its cage. Follow the llama to its home. If you play the drums, the lava will turn into water and you can swim to where Lanky is waiting.
This poor guy is hanging from the ceiling in a cage in the Frantic Factory stage. If you want to free him, you'll have to use Lanky. With the handstand (which is acquired from Cranky in exchange for coins), you can climb up diagonal vent pipe and find a switch, which Lanky should stomp to free the last Kong.
How do I free the monkey in the cage in the Frantic Factory stage?
Use Lanky's handstand (you get it from Cranky) to climb up a vent pipe and hit a switch.
Can I catch the giggling fairies?
Yes. In fact, that's a major part of the game. When you see them in the early stages, memorize their locations (or write them down, or look in the section of this guide that talks about them). Around stage three, Tiny learns a skill that allows her to shrink. You must use that skill in the DK Isles to find the hidden Banana Fairy. She lives inside that island that looks like a head. Use Cranky's shrink barrel, then enter the area to receive a camera. You can now find film in the levels, and you can take pictures of all those annoying fairies. Now backtrack and catch all the old ones. When you collect fairies, you sometimes get rewards, including unlimited ammo and crystals when you have found all 20.
What do I do with those patches of brown soil?
Throughout the DK world, there are patches of brown soil with the letters 'DK' on them. You can't do anything about that until you have talked to the Banana Fairy. Once you have, go to such a patch of soil and use the new move she taught you. That is, hold down the 'B' button until you are charged, then release it. Each soil patch hides a special rainbow coin that gives each Kong 5 coins.
Where can I find the Rare and Nintendo coins, and what good will they do me?
You need these coins to finish the game. In the last level, they provide an entrance to a room that you must visit in order to fight the game's boss. They are hidden in two different places, and you win them by playing games.
You find the Rare coin after you play the Jetpack bonus game. To play this, bring 15 Banana medals to Cranky Kong. The bonus game is easy to win if you stay around the middle area of the screen, collecting items. Remember to shoot constantly, even when none of the asteroids are in sight. You can build the rocket and launch it off, but that only makes things harder and isn't necessary.
This one is harder to get than the Rare coin. In the Frantic Factory stage, you learn a skill that allows Donkey Kong to pull huge levers when he stands on a footpad. Go to the room with the old Donkey Kong arcade machine and pull the switch. Now keep playing until you win. You'll get a banana, but the fun isn't over. Play again. This time it'll be a little harder, though only the first stage really grows much more difficult. If you win this time, the Nintendo coin is yours to own.
How do I finish the third level in the Donkey Kong arcade game?
It's all a matter of timing. If you're stuck in this stage, chances are you're stuck at the last ledge, where you must race to the ladder where Daisy waits without springboards clobbering you. Once you are on the same ledge as Donkey Kong, stand directly over the ladder and watch the springboards until you understand their pattern (just don't watch so long that your time runs out). They bounce fairly high. So, wait until one is at the base of the ladder you must climb to reach Daisy. As it starts to bounce up, immediately run left and climb up the ladder. You must run full speed. Ignore what the springs are doing. You'll either make it or you won't, but this is the only way that practically guarantees a successful attempt.
How do I change from day to night in the Forest Fungi stage?
In the main area, there is a giant tree with a fenced ledge attached. Cannons positioned on the ground around the base of the tree will launch you onto the ledge. Once there, you'll see to images, one of a sun and one of a moon. Shoot one or the other to change the time of day.
How do I enter the Hideout Helm stage?
The first problem is even entering the mouth, which serves as the front door of the level. To do this, you must use Tiny. There's a teleport at the base of the stage, which you use to get to the top. Once there, work your way around and hop over a small gap to land in the open mouth. Once inside, you need to shoot the switch on the opposite side of the wide pit of lava (use sniper vision). You'll also want to use Chunky to turn invisible and make vines come within reach. You can use the vines to cross over the lava.