Can someone compare the PowerShares DBA to the two exchange traded ETNs for grains GRU and JJG? Specifically:

1) What is the method that each of these is using to invest in commodity contracts, and what is the mix of current month and forward month contracts?

2) What is the commodity mix of each of these?

3) From a tax point of view, which are paying dividends or at least trading just as stocks, and which are "partnerships" that result in Schedule K-1 income? I understand DBA is a living hell at tax time because of the requirement to pay tax against income of the partnership, even if there were no distributions made.