Using Firebird 1.5 & BCB 5.0

What is the best/simplist way to accomplish these things.
(My searching found results on UPDATE, FETCH & REPLACE INTO, but no
exact examples of what I want to accomplish)

1) I have a table with 15 columns & 256 rows, col 1 is the PK, .
I want to update all the columns (except the PK) in row x after a
select from row y.
i.e. copy a row to another row

2) As above but with x & y being a range e.g. y = 1 to 20 & x = 51
to 71 i.e. copy 20 rows.

3) As 1 & 2 above but with with the source & destination rows
belonging to tables in a different database.

Thanks for any help.

Jack