Best avoiding the Crossfire as it is notoriously unreliable, the Crossfuse is a much better bike using the Bosch system otherwise Wisper, Woosh or Juicy for non Bosch.
You certainly have got your moneys worth out of it, I have been using a Wisper 905se and a Carrera Crossfuse around the Peak District for the last 3 years and clocked up about 4000 miles, It is a great place to cycle.
Saw this on ebay not far from me, personally I thought it was overpriced, I have had a 905se for over 2 years now and it has been excellent and that is the one I would go for ( until the new Wispers arrive)
Hi, Personally I would go for a folding bike with 20" wheels they are more stable than 16" , Viking do a fairly reasonable folding ebike also try looking in Halfords , if you can up the price then I would choose either a Wisper/Woosh or Juicy.
Surely yes, I have had a Crossfire (terrible cut outs) and have a Crossfuse ( brilliant) with Bosch motor, I am sure you will get on great with the Cube.
Mid drive conversion would be very tricky due to the fact the bottom bracket has Raleighs propietary 26 tpi size and the shells are wider than standard at 76mm unlike the Dawes Kingpin which are standard.
Personally I am not that keen on that blue I prefer the misty blue or the iridium or black/grey, either way I am looking forward to a test ride and possible upgrade from my trusty 905.
Deffo no problems regarding brakes it is common for these bikes to swap for 406 wheels off bmx and such as the wheels are lighter and give better braking.
A 1000w is going to be illegal also you will have to modify the rear drop outs to do that and lose the 3 speed Sturmey Archer gears. I have seen a few conversions with front wheel drive, plus a significant amount of 20" wheel electric bikes are front hub motors. I used to own a viking 20" front...