I did something similar except I put mine much closer together and kept the pics on top row at same height. I also switched my frames to one color but they were all different sizes. It came out great.

You can go lower for sure. The "rule" seems to be to not go higher than the door. I personally love pictures in a hall way, but an entry way is nice too. A tip would be to put them down on the floor first and see how you want to display them before hanging them.

If you can fit a narrow table, you could do something like this: