I can't speak to your marketing questions, but another aspect to consider is the FAA 135 certification process. It is lengthy and frequently overwhelming if you have never been through it.
Even if you pay a consultant firm to prepare documents, such as the PASI and compliance statement, you still must be actively involved and very familiar with all the requirements. If you have not yet done so, research FAA Order 8900.1, Volume 2, Air Carrier Certification Process so you will know what to expect. It could take a while just to get to "your turn" in the CSOP queue if FSDO resources are tight (most likely they are) due to staffing, retirements and hiring freeze.