The PCI-6035 is grouped with the 6034 and the 6036 E series boards, so you can find any of the specifications on the data sheet for that family. Here is a link:
http://www.ni.com/pdf/products/us/4daqsc202-204_ETCx2_212_213.pdf
In reference to your question about the amount of current that is sinked through analog input operations, it looks like the input bias current is specified as no more than +/- 200 pA (pico amperes).
I hope this has helped.
Jason
