I think the good choice will be the S3,
Either the S3 cooler or the Forge cooler are both very good, and both have different advantages and disadvantages. However, if you live in a hot country, and use the air con a lot - then the Forge has very clear advantages over the "OEM placement" of the S3 cooler.
I have seen APR insturction, they remove the complete front panel and headlamps to do it, I dont wish to mess with it.
Removing the bumper is no problem,
If you have a look at the Forge UK website, they have a colour downloadable PDF comprehensive fitting instructions for the Forge unit.
Furthermore, if you look in the "maintenance and info" subsection of this Mk5 forum, you should find my sticky thread for "free workshop manuals":
http://www.golfgtiforum.co.uk/index.php?topic=54324.0, which has PDFs of factory manuals for removing the "lock carrier" - also known as the bonnet slam panel - which holds the standard air con condensor, intercooler and radiator. It isn't difficult, but it is quite time consuming, and requires some "out of the box" thinking, along with ideally a 2nd pair of hands.
Can you remove the intercooler without removing the front panel 
If you mean the standard OEM cooler, then no.