The Oppo 103 is a fine player, but the 105, when it comes out, (or current 95) has better DACs and is meant to be used when you want very high quality D to A, more than what your receiver can give you. This is particularly important for 2 channel music. Many of the mods out there do a similar thing. With the 103, the expectation is that most of the time it will send a digital signal to a receiver and the D to A will be done in the receiver. The big jump up to the 95 or newer 105 is for the better DACs and everything that goes with it. That said, many people are happy just using the DACs in the 103 or in their receiver. The 105 also has a USB input for use of a PC as a source. The 105 is $1,200, so it is a significant price for the upgrades. Sounds like the 103 should be fine for you.
DVDs and Blu-Ray disks are encrypted to play in only certain regions So a US disk (region 1) will not play in Europe, for example. Oppos sold in the US only work with US (region 1) disks. The zone free versions are after market mods that allow the US models to also work with disks from other regions, like Europe. If you are using US disks in the US, the region free mods are not necessary.
DVDs and Blu-Ray disks are encrypted to play in only certain regions So a US disk (region 1) will not play in Europe, for example. Oppos sold in the US only work with US (region 1) disks. The zone free versions are after market mods that allow the US models to also work with disks from other regions, like Europe. If you are using US disks in the US, the region free mods are not necessary.