My Korean is pretty bad, I'm better with Vietnamese, but from what I can gather the second one is a hot pepper, probably Sansho or similar variety. If I translated the melon right, I think it says something about 'super sweet and chewy.' But I'm pretty sure that is supposed to say 'tasty' or 'crunchy.'
Hopefully someone has a better translation.

-Colby

The first one is a hot green pepper type. This type is usually used in green. Immature young ones are not much hot and used in stir fry and salad, but mature green ones are slightly hot, but less hot than jalopeno.
The second one is a sweet pepper type. Young and immature ones are sweet but old one is mild hot. Generally used in stir fry.
As you gussed well, third one is watermelon. The packet says this variety has very clear zigzag color outside and sweet taste.

Many, many thanks to you both! :)

I hoped that the second (wrinkled)pepper was a shishito type of pepper and it sounds like it probably is. The seed pack photo looks very similar to a picture of 'Green Twist' Hybrid Shishito I found on the internet offered by another Korean seed company. I played around with an online translator and it looked to my ignorant eyes that the package does have the character for "twist."

Thanks again for the help ScarletRose and Colby!
Danita