Nope, thats why they work so well as companions - fancy mice can't breed with the soft furs
I'm afraid I can't guarantee any info on soft fur care as while I have researched them it was a while ago. This website is usually my go-to for any exotic rodent info -
Multimammate Mice
Yeah natural toys are great for mice
Ours have lots of bark climbing frames and things like that although I am careful getting them out of boxes now (inhaling some dust from one caused a cough thats not cleared yet and its over three weeks later!)
We used to feed the Mr Johnsons rat and mouse mix (I think thats what it was called) and mixed it with other mixes, I can't see any harm in doing so
What we do now is make our own mix based on the shunamite rat diet but with adjusted percentages so its more suitable for mice, it might not be too practical for a single mouse but it works well for our 22 of them
It'd give you a lot of freedom with the mix - thats a big part of why we've switched to it.
Er... One wheel is probably fine for a few mice, we tend to use a few wheels per cage (unless theres just one mouse in it) but two wheels'd be more than enough for three mice. We use silent spinners but multimammates (soft furs) are bigger so you may want a bigger wheel for them. Multis are also very, very chewy which could pose a problem when it comes to wheels for them. We don't have a set ratio of toys to mice in our cages, if anything is particuarly popular we do give multiples but we've had fourteen girls living happily with only one of most toys