I've never prepared From 5330 before, but here is my take on the instructions: Items C, D, E, F, G refer to the employer, in this case yourself as self-employed. For item C I would probably just say "SEP-IRA." For item D you can repeat your name and address. You probably don't have an EIN since none is required for a SEP plan, so I would leave item E blank if that's the case. SEP plans are calendar-year plans, so for item F the plan year ended 12/31/2018. For a SEP plan there is no plan number, so I would leave that blank.
This is not a prohibited transaction, so nothing goes on Schedule C or on Part I lines 3a/b.
Regarding Schedule A, in addition to what you listed you'll also have $601 on line 3.
