4th year Aeronautical Engineering ...If there was one within a 20 miles radius I might ...
Is the weather radar necessary if the EFB can provide immediate weather information?
... "radar" I assume you mean wether radar?
Any idea on maintenance costs for a GNS 430W?
why is it occasionally that aircraft are fitted with 2 identical GPS units?
£6594. Sounds pretty expensive
no need for IFR equipment? Just an iPad?
anything I could do with the landing gear to improve DOC?
Indeed, if it is too late for you to change school or vocation, I highly recommend you should consider working as a trainee in a reputable aircraft maintenance shop and learn some basics. As it was suggested earlier, you should also make a point to go to some aviation events such as AeroExpo, AirVenture, Avalon or similar. Even if they are more than 20 miles away.
Spend some time in and around airfields and learn at least something about general aviation, avionics, aircraft systems, etc.
Of course, there has to be DESIRE, without some degree of desire, interest and passion, all is pointless.
Now I better understand why some aviation technocrats, out of so called "aeronautical engineering schools," and end up in SMS, maintenance planning, parts purchasing, audits, etc., are creating so much havoc in the industry and, have no clue whatsoever of what they are doing.
PS. To your latest question if you need a WX radar (vs. EFB or MFD uplink weather only): you should know that the mosaic of data displayed on your MFD is far from being
"immediate" as it is obtained and processed from multiple NEXRAD sites, the information could be more then 20 minutes old (cf. NTSB safety alert on limitations of cockpit weather displays).