Check the inter cooler hoses for splits, usually the long one on the left hand side of the engine looking from the front. The hose often rubs through on the bracket on the inlet manifold.
When changing my filter I found there was no need to drill out the rivets as they had already corroded through leaving the pump and filter held in place by the pipes.
The unipart pads fitted when I bought my Freelander squealed from the word go, turned out that the dealer had incorrectly fitted them, unipart pads have a bigger chamfer on one pad unlike some other makes.
If the long inter cooler hose is original the lower clip is usually inaccessible, using a small open end spanner on the clip will make it easier to unfasten.