Please check the website of the Federal Foreign Office.

The Schengen visa allows entry to all countries which are members of the Schengen Agreement. The visa can be issued for airport transit, tourist stays, visitor stays and business stays.
There is no legal entitlement to enter the Schengen area. The responsible border control authorities of the Schengen states check compliance with all requirements of the Schengen Borders code and decide whether to grant or deny entry.

Yes, you have to apply to the embassy of the country which is your main destination, generally the longest stay.

• Valid national passport, valid for at least three months after the expiry date of the visa (and copy of the ID page)
• Fully completed application form and declaration duly signed
• Two passport photographs (not older than 6 months, size 3.5 x 4.5 cm, light background). Hats or head coverings are generally not permitted, but an exception can be made in particular for religious reasons. If a head covering is allowed, your face must be visible from the chin to the forehead. Any changes or modifications of the photograph are not allowed.
• Korean Alien Registration Card, valid for at least 3 months after travel dates, plus one copy
• Flight reservation (round trip) and travel itinerary
• Proof of applicant’s return to home country after travel (certification of employment (not older than a month) / employment contract or other information proving employment / school or student certificate / proof of business registration and tax form / proof of immovable property)
• Vacation certificate from employer
• Proof of secured financial status (bank statements from the previous 6 months)
• Proof of accommodation (e.g. hotel reservation / proof of possession of own real estate / confirmation that a host will provide private accommodation)
• Original invitation letter of friends or family specifying the relationship between applicant and the inviting person, name and full address of the inviting person and/or formal obligation (Verpflichtungserklärung)
• Confirmation letter from your health insurance showing coverage for emergency medical treatment, outpatient transportation, transportation to home country covering a minimum of 30,000 euros, valid in all Schengen states for the entire duration of the stay.

• Valid national passport, valid for at least three months after the expiry date of the visa (and copy of the ID page) Fully completed application form and declaration duly signed
• Two passport photographs (not older than 6 months, size 3.5 x 4.5 cm, light background). Hats or head coverings are generally not permitted, but an exception can be made in particular for religious reasons. If a head covering is allowed, your face must be visible from the chin to the forehead. Any changes or modifications of the photograph are not allowed.
• Korean Alien Registration Card, valid for at least 3 months after travel dates, plus one copy
• Flight reservation (round trip) and travel itinerary
• Proof of applicant’s return to home country after travel (certification of employment (not older than a month) / employment contract or other information proving employment / school or student certificate / proof of business registration and tax form / proof of immovable property)
• Vacation certificate from employer
• Proof of secured financial status (bank statements from the previous 6 months)
• Proof of reason for travelling (e.g. booked tours, travel plan (itinerary))
• Proof of accommodation (e.g. hotel reservation / proof of possession of own real estate / confirmation that a host will provide private accommodation)
• Confirmation letter from your health insurance showing coverage for emergency medical treatment, outpatient transportation, transportation to home country covering a minimum of 30,000 euros, valid in all Schengen states for the entire duration of the stay.

Generally not, unless you applied for the job and permission was explicitly granted in the visa.

This is generally not possible.

If your visa is valid for all Schengen states – including Germany – you can enter all Schengen states regardless of which state issued the visa.

If your visa is valid for all Schengen states or the states you would like to enter, you can enter all Schengen states regardless of which state issued the visa.

For the majority of foreign travellers, the “airport transit privilege” applies: If you don’t leave the international transit area and the final destination is a country outside of the Schengen area, you don’t need a visa for your transit stay.
Current information regarding the airport transit visa obligation can be found here.

Required documents for a transit visa

No, this is not possible.
You can, however, have your passport sent to the Consulate in Busan after your application has been processed.