What concerns are there with running high frequency traces?
Start with the vendor's data sheet. They have lots of details.
Make sure each leg of each pair is the same length.
Since the signals are differential, EMI, etc. tends to effect each of + and - the same, so it isn't as bad as you expect.
Keep in mind gigabit Ethernet uses all 4 pairs bidirectionally, so don't read too much into the RX and TX names.
You need a transformer between the MCU and the connector.
You can put the pairs on the same layer. If so, just keep the pair to pair spacing more that the spacing within the pairs.
Do run over a ground plane.
Don't run over a split in a plane.