Congrats on the tank purchase, my advice is to be patient and not get over anxious to start cutting into the tank just yet. Do some initial planning and layout to get a feel of what you are going to build. Tire selection and ride height will dictate a lot, and the decision of whether to flatten the bottom of the tank or not. As others have mentioned don't underestimate the space required for safety gear such as a head and neck restraint and fire suit, very important to incorporate very early on.
In addition to the frame table I would suggest some way to rotate the frame on a rotisserie to make welding and work on the bottom easier. I found myself doing almost as much work on the bottom of my car as the top.
Overall good luck, and don't be afraid to ask questions. In my opinion (not that it's worth much) patience and determination are key to getting through this process. It took me 5 years to build my bellytank and there was plenty of low points when it felts like it was never going to be finished. But it is all worth it.
And yes, you will be amazed how strong hose clamps and angle brackets are holding a roll cage together.
Andy
