I think a lot of people are making this a lot more then it is, if your in Melbourne just take your ecu to a shop that deals with them and they can put a new base map in it just so it's safe to start... No big deal
I highly doubt your engine will be siezed after 3 years.
Get a new fuel filter, put in new fuel hook up a battery the right way and see what happens (after you get a new base map) , even if some of your injectors are crap it should still start ...
Motors only need 3 things, air, fuel, spark.
Check your air filter too it maybe clogged up with shit which won't help.
You don't need new gas tank, new lines or a hoist or car stand..
Driving it may be different, brakes and bearing etc may need attention, if you've left the hand brake it it's more than likely stuck