Yes, but after 128.000 bricks the next bricks stops rendering, you cannot see them but they are there physically because you can touch them but it's like touching an invisible wall.
No, after 131,072 (2^17) objects they stop rendering. there is a buffer zone of 3,072 objects so, let's say you have space for 3,072 vehicles and such.
The amount of datablocks may affect the limit.