Wheel Arch & Liner Screws - which to buy?

Trying to get access to my dead Webasto FBH heater to see wassup, via removing the nsf Wheel Arch Liner. Failing this I will try then removing the Front Bumper.

On trying to remove the Wheel Arch screws, the screw-top cross heads are all rotten and every one will need drilling out.

Can anyone advise what specific screws these are to replace? Do they screw into metal or plastic? (the 2 'underneath' facing the road and the two at the inner front of the Wheel Arch)

The 'screws' are actually those plastic hobbies that push into a fastener. Use a small screwdriver to lever the screw part out and then pull the lot out with your fingers.

Those screws on my 98 FL1 are about 30mm long and the screw into a metal clip that clips onto the plastic liner. Not counting the front mudflap there are two under the outer edge of the wheel arch, and two further forward and lower down. Same for both sides.

The front guard isn't to bad to get off. There are two screw bolts / studs [8mm hex' head] at the bottom of the A pillar, two more at sill level. Then it's the ones along the bonnet line and the last two are a bit tricky. The first is up high near the indicator bulb change hatch it's a 10mm hex head. Gently prise / pull the guard out from the front and you can get to the last tricky one. It's an 8mm hex head that goes into the a bracket between the door hinges inside the guard.

The bumper is the four phillips head screws on the closing panel - the panel you look at when the bonnet is up, it has the info stickers on it, then the three? studs by the lower air intake [plus the four screws that attach to the arch liner mentioned in the first paragraph], wiggle and pull it forward.

If you do take the front guard off check for corrosion at the front end of the sill behind the mudflap.

Get a dremmel and cut slots into the screw head so you can use an ordinary driver to get them out, never had to drill one out yet.
Replace with stainless screws

Thanks for the helpful info.

Sadly, mine were literally rust-welded, I have some Iron-Age artifacts in better condition than these ;-)

I had to drill away the heads and bend the remaining stalks away so as not to rip the arch-liner holes for them. The new clips and stainless steel screws should be much better.