E80 upgrade to axiom9rv

Hello new to forum and trying to understand exactly my needs and thus my costs concerning upgrading my existing system which consists of an E80 MFD with a DSM30 module, sr100 module, Raymarine high speed sea talk network, model 218 vhf radio and a thru hull transducer .
I am looking to upgrade to Axiom 9rv mfd. what do I need beside the MFD? One or two thru hull transducers? What models? Thank you in advance
Ed