Ok so here is a brief, yet long-winded, bit of inf

Ok so here is a brief, yet long-winded, bit of information that I hope can help some out...as I mentioned before, I do have extensive experience in the aviation profession as a pilot and regional airline owner (as well as Part 135 and 91 charter operations owner). The certification process to add aircraft with the FAA is an extensive process. It is not as simple as paying some money, getting it added to the cert, and calling it a day. Each type of aircraft being operated has to be approved and added to the company provided documents (which is a large task), operational procedures, approved MEL's (minimum equipment lists), maintenance training and pilot training, both current and recurrent. The aircraft itself has to undergo scrutiny along with the crew and management. This is the tip of the iceberg to this process.
More so than money, it takes TIME and ENERGY. An exhausting and overwhelming amount of both....so, if you already have an aircraft that is approved for flight (ex, Boeing 737-xxx) and you are a new, restructuring, or aspiring airline, it can just simply be too much at once. There is a steep learning curve in this business, and it's not like any other business (the reason I now own other business ventures outside of aviation!). It is highly regulated, which makes it highly expensive. The management listed on the USGL site is more than suited and capable of handling it based on their profiles, but I am sure at the moment they are strictly focused on the one 737 and acquisition of Songbird (I hope).
Nothing happens fast in the FAA, except violation investigations, and even those take an absurd amount of time. The more you give to them at once, the slower they move....so in my personal opinion, I would operate what I currently can operate as laid out on my certificate. I would get a good business established in an expedited manner with what I have at my disposal without any added headaches or FAA involvement. Once the dust settles and I have things running smooth and everyone on the same page, then by all means, take that next step into whatever additional aircraft you can afford to operate and fill seats. 737 pilot initial and recurrent training is a lot cheaper than a 777 or 767 training, and there are alot of 737 typed guys out there that can save some money, initially at least.