You didn't say in your Post if you're doing the work yourself or if you're hiring a Contractor. If you're doing the work yourself, I'd spend some $$$ and hire someone to at least design EVERYTHING that you don't know how to design yourself. Obviously, if the 'base' is not done correctly, the rest of the construction project is going to end up on the ground! Sometimes, it pays to spend some of the $$$ you're saving on sound, safe advice, such as that of a Structural Engineer. It will go a long way.
Now, assuming on the other hand, that you've hired a Contractor to do the work, ... well, what does he say? You can forgo this option and use a poured footing and foundation instead. In either case you don't want to tie the new construction footing/foundation in with the old. They will most likely 'move' differently since they weren't built together.
Other than those thoughts, I suggest you contact a Block Mfgr for how-to manuals, or visit a bookstore or library to see what you can find. My best to ya and hope this helps.