Make sure your game is up to date. Sometimes the automatic updater gets confused. About games being sold on disc - my opinion is in the near future as cloud computing becomes common place and SecuROM (drm) is accepted, physical distrobution of software will disappear. Tombraider 2013 is download only and you have to have a Steam account. I have seen a trend that optical drives (cd, dvd, br) will not be a standard item. Some laptops don't even have them. Being connected to the internet is not going to be an option.
The exchange items are NOT checked and may require items from a pack you don't have or are not created properly. If free store items install then the problem is probably with the exchange item. If store items won't install then there may be a problem with the game installation. I can say I have bought venues and items from the TS3 store and have had little problems.