No matter how many times i go, I never see the redfoots, or any tortoises other than the sulcatas. I can never find them Sorry i know this is an old thread :l
I like the common toads (Bufo bufo) over here. They so cute and squishy lookinh ^.^
Also i find Great crested newts intresting but they are protected here! :)
I love your enclosure. And i would say no to mixing as all tortoises pick up different disease etc and all species have different immune systems due to where they originate from.
Box turtles and RF's diet are very similair!
Red-foots need high humidity (80%) And heat. (75-80o cool side 95-100o basking spot)
Red like to hide alot...so plants and hides! etc...I cant answer much more as you've not asked anything specific!