Depending on your power expectations quite a few mods will be required for the car to be 'usable' with increased. letting you'r engine 'breathe' more will do you wonders so a FMIC and downpipe would be essential, alongside an ECU tune. the OEM air box and intake on our cars is already good for up to 400bhp as recorded in
@TarmoT build thread, but quite a lot of members have still upgraded this system, also the addition of an air intake snorkel to help feed fresh cold air into the air box will be a great addition.
the restricting feature for power on our cars is the turbocharger, you won't safely achieve over 320ps with our stock turbo, so if your looking for anything above, that will need upgraded.
with the addition of extra power, you'd want to upgrade your upper and lower engine mounts as well as change to some good tires such as pilot sports 4 or 4s as this will help you get a lot more grip and eliminate wheel hop in the wet.
Using a piggyback vs a tune is personal preference. if you want to keep engine warranty then don't get a tune. but a proper ECU tune will always beat a piggyback hands down.
as for accelerated engine wear I can't comment too much on as I don't think there is enough documented data on people running big power for quite a long time, due to the cars age. But you'd expect running high boost pressures would have some negative effects over a long time on the stock internals as the engine block is 'open deck'. What I can say is you'd like to upgrade your clutch for sure anything past 320ps if you plan on giving it the beans.
There is enough build threads and data from various members on here that will tell you all in detail, and I'm sure if you look at members such as
@R Veloster N,
@TarmoT and
@Dan_bush27 you will find all you need to know about our engines capabilities!