I used to own an 2005 Honda Accord V6. (I sold it because I bought a 2013 Accord V6; it was in good shape when I got rid of it.) With respect to the seventh-generation, my research indicated to me that transmission issues were primarily limited to V6-powered vehicles in model years 2003 and 2004.
Your Accord falls under neither of those categories, so I wouldn't worry about it more than I would with any other car at your level of mileage.
As for your oil - basically any 5W20 or 0W20 will do it, so long as it meets API SL (ILSAC GF-3) standards or better. Basically, just buy a reputable brand (Mobil, Pennzoil, Quaker State, Castrol, etc.) from your local hardware store or Wal-Mart.
I wouldn't worry too much about your Accord's engine, the K24A4. Based on extensive experience in BITOG and elsewhere, it's known to be a very stout engine that's easy on oil.