You can get detailed information about each product on the product specific information page which includes links to manuals and other documents under the Resources tab. For example for the SCXI-1125 go to http://sine.ni.com/nips/cds/view/p/lang/en/nid/3669.
The lead-free spec is called RoHS. Did you search the site for that? There's a listing of RoHS boards at http://zone.ni.com/devzone/cda/tut/p/id/4581 and there is also a FAQ listed at the bottom of that page.
p.s. not sure why you posted this question to the real-time board.