I just plowed through this same issue with the oscillator on the MCIMX6G2DVM05AA and found the erratas and documentation somewhat lacking in detail and urgency considering how messed up the first mask set of the part was; I hope this response is helpful or that you've already resolved it. The problem is that on MCIMX6G2DVM05AA, mask 0N52P, and presumably others like it the main oscillator is completely broken. This was fixed on MCIMX6G2DVM05AA, mask 1N52P (note that the part number didn't change, just the mask set version). If you have parts with mask set 0N52P you cannot use a crystal since the on-board oscillator does not work. Instead, you need to use an external oscillator. However, since the internal oscillator is well and truly broken you can't just feed the 24MHz into the XTALI pin because it doesn't make it through the internal inverter. Instead, the recommendation is to drive it into the XTALO pin. However, to be sure you don't exceed the 1.1V NVCC_PLL supply that the oscillator section runs on you need to divide down the 24MHz as you feed it into the XTALO pin. The divider should be 1/3 so 3.3V / 3 = 1.1V. The MCIMX6G2DVM05 EVK schematic has 1k and 499 ohms which yields 1.1V. I don't know why your EVK schematic shows 1k and 2k; that would yield 2.2V which is too high.
I don't have any answers on your other questions. I hope this much was helpful.
