[GhostsInSnow]

Personally, I wouldn't go with a trio as there is a risk of 2 ganging up on 1. A pair would be better, however, they can fall out even months down the line so it's important to get their environment right and look out for signs of fighting.
You'll need 2 of everything ideally so 2 wheels, 2 water sources, scatter feeding is best with pairs and groups to prevent becoming territorial over food bowls (and it also provides extra enrichment). Any hides and toys you use should have multiple exits to prevent one being cornered by the other and try to avoid adding levels as, again, they can become territorial over these
My previous Robo's have all enjoyed the opportunity to dig and burrow so deep substrate is a good idea. I've not noticed a huge difference in temperament between the males and females personally.
Like I said, look out for signs of fighting so sleeping out in the open, one looking skinnier than the other, excessive squeaking, wounds and fur loss. If this does happen you'll need to separate so I'd advise having a spare cage on hand in order to separate straight away if you notice them falling out. If they do, you'll need to keep them separate going forward.
Don't stress them too much but it's a good idea to get them used to at least basic handling so that, if you need to, you're able to take them to a vet.
If you do need to take one anywhere, it's best to take them together to minimise the risk of falling out