The "pockets of the GP" is not a general partnership purpose. General partnership purposes could be pipeline maintanance, repairing equipment or any of the thousands of things EPD spends $$ on every day.
The units are down about 2.5% because the public pricing of the units will be under the market by about that amount. To see what happens with an offering take a look at MWE and its recent offering.
This should bring EPD about $450M. With their retained cash for Q1 and Q2 that should put them needing about $450M in debt to complete the $1.2B purchase. This would mean about an $18M saving in interest on the $300M in retained earnings. Also a tiny step closer to a higher bond rating.
Thanks for the explanation; it seems odd that the things you mentioned are typically listed as 'general partnership purposes'; seems there should be a better way to refer to these uses of funds such as development or maintenance purposes; no?