brendon,
this whole smart home/retic controller/ac controller thing would be way easier to do with a PLC (programmable logic controller). It's very doable and i've been thinking of doing it myself, just can't find a donor PLC at the moment
(ie a job to pay for one).
it might not be everyone's cup of tea but a touch panel + plc setup would look great imo and best of all programming these is easy (well i know how and i still owe you a favour)