The ATF says that you must obtain an FFL if you "intend to engage in a business". They don't specify how much business you must do, or how well you must run this business. You just need to do some business. In today's day and age, it ain't that hard to find customers who need to do a transfer. I bet that includes say least one of good existing clients. Don't invent impediments that don't exist.
The first thing you need to do is to research your local zoning regulations, because almost nothing else shy of a prior felony conviction will bring this process to a screeching halt any faster. Assuming that you don't find anything obvious in the regulations, make a face-to-face appointment with your zoning official, be nice, and confirm that what you're trying to do is acceptable. You'll need to get this in writing now or shortly after the ATF begins to act on your application, so behave accordingly.
Next, form your LLC (assuming you don't do this under the existing corporation), complying with the laws in your state. Get a local business license if necessary. Make sure to get a federal EIN. Open a bank account. Get a state sales tax license; it's not necessary for the FFL or SOT but you'll want to have that when setting up distributor accounts.
Now, complete your FFL application accurately. Don't misspell the name of your company or select the wrong type of license or anything like that. My ATF guy said it's rare that the applications are correct and accurate, and it's a big pain in his ass and the second most common reason for denying a license application (the first is local zoning regs). Think of this as a first-other filter; if you're too dumb to fill out the application properly then you may not make it as a gun dealer.
Assuming you've done all the correctly and that you can pass the background check (generally the same as that for purchasing a firearm + verification that you haven't previously lost a firearms license), you just need to not screw up your "interview" (really a three-hour-long review of dozens of forms). Take notes, ask intelligent questions, try not to fall asleep, and you'll likely pass. Wait a few weeks and the license will show up. It's that simple. The SOT is a separate deal, and it's not anything more than a receipt for paying a tax.
Transferring most Title II items in/out of the entity is straightforward. You'll need to file Form 3s for transfers between SOTs but those typically clear in 1-2 weeks. Machine guns (specifically anything post-'86) are another matter entirely and well beyond the scope of a forum post, particularly considering the attention they've recently brought to some big names.
SOT items will be owned by the corporation and so that's going to determine succession in case of the passing of the corporation's member(s). Such matters are well above my pay grade and best discussed with your local attorney.