looks like a good plan to me
A field flattener makes the scope work properly out to the edge of the camera chip. Scopes generally have curved focal planes - not a problem for visual use, but worth tidying up for imaging
EVF is probably OK provided the camera provides an enlarged view on the finder or viewing on a computer screen to help you do manual focusing. Maybe someone who has an A65 can help.
also, some of the articles in the beginners section in this are worth a read
http://www.iceinspace.com.au/projects.html