Great question. The most important soil characteristics for aloe plants are good drainage and that the soil does not hold onto moisture for too long.

If your aloe is thriving then I suspect you have created an appropriate potting mix for your aloe that effectively replicates the balance of inorganic material (the white sand) and organic material (the potting soil) for good soil drainage that aloe plants require to stay healthy in their native environment.

As long as the soil dries out between bouts of watering your aloe should stay healthy.

A good way to test this is by feeling the soil at the bottom of the pot through the drainage holes in the base of the pot. If you can detect moisture then delay watering. If the soil feels somewhat dry then this is the optimal time for watering with a generous soak (typically watering aloe once every 2 weeks is a good schedule, read my article how to water aloe vera for more detail on this).

As long as your aloe is healthy I recommend that you do not change the soil. However if the aloe leaves turn yellow, brown or black then overwatering or damp soil is usually the cause, in which case scale back the frequency of watering and change the soil to succulent and cacti soil.

In reference to your other question, aloe plants do not separate as such but they do produce offshoots which can be separated from the main plant (there is a photo of this half way down in my article choosing the best pots for aloe vera).

Aloe vera is also very easy to propagate from leaf cuttings which is a great way to reduce the size of your aloe and create more plants (there are some great tutorials on YouTube).

It is also worth noting that aloe plants in full sun stay in a more compact shape, whereas aloe plants in less sun grow taller ( as they look for more light).

Please feel free to ask, if you have any more questions or need any more clarification on this!