Okay. I noticed you are very new to maplestory. I'll answer your questions. To jump down, you must hold the down button while pressing Alt (jump button) to jump down. It very vital to learn that since it makes travel around maplestory easier.
The soft keyboard prevent malicious ware like keyloggers from getting your pin. Even if the get the password, they will never figure out the pin since it's used by a mouse. Keep all virus, spyware and other protections up.
Don't worry. You'll get use to it. 
