how do I align this to match GD&T so it can be correctly dimensioned?

Datums A & B are using datum target areas so the easiest way to do it would be to measure auto planes for A1, A2, B1 & B2.  You can set the XYZ centre co-ordinates, switch the hit pattern to radial instead of square, and then use the spacer to define the Ø10 area (spacer = 5).  Once you've measured them all, you need to construct BFRE planes using the hits, datum A plane from the hits of A1 & A2 and datum B plane from the hits of B1 & B2.  You can then open the datum definition dialog (insert>dimension>datum definition), pick the constructed datum A plane for datum A, the constructed datum B plane for datum B and then click the "common datum" checkbox and pick A & B to define common datum A-B.  For datum C, you would need to measure the 3xØ6.6 holes (ideally as cylinders rather than circles).  and In the datum definition dialog, you would pick all 3 holes when defining datum C.  The same approach would be required for the 3xØ4.79 datum D holes.  You can then measure the rest of the part and add geometric tolerance commands for the various callouts.

If you wanted to create alignments that replicated the datum reference frames it would be a little harder.  For example, to doyou would need to construct another BFRE plane for datum A-B from all of the hits of A1, A2, B1 & B2 - assuming they are all at the same height - this would be your LEVEL.  You would then need to add a 2D rotate & translate best-fit of the 3x datum D holes.

if I were to try to align but A and B are NOT on the same work plane, would you use a midplane for the level of the alignment?

if I were to try to align but A and B are NOT on the same work plane, would you use a midplane for the level of the alignment?

offset plane.  select all the points on all the nets for the plane construction, then select tick OFFSET, then click on offsets, then tick calculate offsets, then enter the nominal vector for the plane, and click calculate

thank you for explaining