Will the on-line registration process eliminate any possibility for claiming the drone expense as a tax deduction? 

Will such registration prevent the use of the drone in any "business" capacity?

I snooped around briefly on the link Tim provided in the frozen post above.  It appears that the regulations are based on interpretations of the laws Congress passed, as is typical of all regulation.

I did not read entirely through this link but it is interesting reading, as is much on the site Tim linked

 https://www.faa.gov/uas/media/model_aircraft_spec_rule.pdf