radiators are really easy - remove 10mm bolts holding the reservoir in place, shrouds/fans via a couple 10mm bolts, remove cooling hoses, transmission fluid lines, and unbolt the radiator from the top. slides right out.
ATF lines are not usually in great shape and you'll need to replace the hose and clamps as they'll be rusty.
there's nothing to it, they are held in place at the top with 2 12mm bolts i think and the bottom just sits on pegs and pulls out easily. the rest is just removing ancillary things to get the radiator out - hoses, electrical connectors, fans.
the only tricky part is if the fan shroud bolts are rusty, they will round off rather quick around here in the northeast and be nearly immovable. make *certain* you start with a 6 point socket and not a 12. if it does strip, I generally just chisel away the plastic around the bolt and leave it, you can loose one bolt and still attach the fans just fine.
on some Subarus you can disconnect the electrical connector for the fans and remove the radiator with a fan still attached - i'm uncertain if you can do that on an 04 2.5L though I don't think you can. but might be worth trying if you have that rusted bolt issue.
