To limit a report to just one record, either:
a) Base the report on a query, and use the Criteria in the query to limit
it,
or
b) Use the WhereCondition of OpenReport to limit it to a particualar record.

For details and an exmaple of (b), see:
   Print the record in the form
at:
   Print the record in the form

I do not understand you 2nd question. In report design view, the Detail
section will always be below any Header section. If you wanted the Detail
section to be above the Header, you need to use a Group Footer instead of a
Group Header. You can add a footer section through the Sorting And Grouping
dialog (View menu.)