Mounting BDR91

Hi all

First time poster here but spent days reading this forum and thanks to everyone who's contributed.

I'm thinking of buying the Evohome system. House is three years old and S-Plan.

I think I'll be ok with the wiring but just wondering about the actual physical mounting of the BDR91. If I remove the existing T6360 will the BDR91 mounting screws line up with the holes on the existing backbox? And am I likely to have RF problems if that backbox is metal?

Thanks

Ian