Although I cannot answer all your questions I don't believe you should depend on internet forums for complex questions relating to visa applications. However, there are some websites where you can obtain reliable information. (Apologies if you have already consulted them.)
EU's own document "
Handbook for the Processing of Visa Applications and the Modification of Issued Visas" states the following (on p.23):
2.1.2. If the travel destination includes more than one Member State, the application must be dealt with by the consulate of the main destination. The main destination is understood to be the destination where the applicant intends to spend the longest time or where the main purpose of the intended journey is carried out.
The website of the
Consulate General of Switzerland, Chicago is very clear about who needs to visit the consulate in person for visa application based on the first 3 digits of your zip code.