EFIN is required only if you are going to be e-filing returns.  And you will need a PTIN also if you are going to be a paid preparer.  To be issued either or both of these numbers, you will be subject to certain rules and have various responsibilities.  The process for being issued an EFIN is particularly onerous for good reasons - if you have no need for it, there is no reason for you to apply.

TurboTax is a personal tax product.  Its license does not permit its use by paid preparers.  If you are a paid preparer, you will need to subscribe to one of Intuit's tax products for tax professionals (i.e. Lacerte, ProSeries, or ProConnect) or one of the professional tax products from other competitors.  It goes without saying, then, you will also need a PTIN (and an EFIN, if you are required to e-file).