I would ether go all flamers or all meltas in that chosen squad. Maximize their purpose. dont go half and half.
The troops... drop that lascannon and perhaps give them a second melta. those marines have to be stationary to fire the Lascannon.
The Pread.. Add a Lascannon and don't use sponsons
As far as a tip I NEVER run zerkers but I have seen them excel and fail due to poor choices. my 1 tip would be GET THE THEIR FAST. So go 12 and pop smoke, then second turn book it 12 again dont be afraid with them they need to get there. use the vanilla marine rhino as a mobile shield when advancing as well.
Hope this sheds some light.
Chaosftw