Ford fiesta mk6 Service questions

[klaudmjj]

I'm planning to service my car myself this month and I have some questions. I'm planning to do the;
Air filter
Oil and oil filter
Flush power steering fluid,
Possibly flush coolant,
Replace the fuel filter,
and change the spark plugs.
Today I took apart the airbox to check the air filter and see if that needs changing. I looked at the breather pipe that's attached from the airbox to the engine and noticed that it has some oil in it should that be normal? Also where the breather pipe connects to the airbox it has a sponge in it, at first I thought it was gunk. I'm guessing the sponge is meant to be light in colour but it is black, and when I touch it slightly it just disintegrates. Is it worth replacing? Would any household sponge do the trick? Also is it worth replacing the air filter?
Here are some pictures.

[InitialDave]

Sponge is just a breather filter to catch oil droplets. I think they're about £3.

[klaudmjj]

InitialDave said:

Sponge is just a breather filter to catch oil droplets. I think they're about £3.

Where can I buy one? I can't seem to find it on eBay or anywhere.

[InitialDave]

Assuming the usual Ford routine of using the same part on loads of stuff:
https://www.ebay.co.uk/itm/254062750708

[klaudmjj]

InitialDave said:

Assuming the usual Ford routine of using the same part on loads of stuff:
https://www.ebay.co.uk/itm/254062750708

Thanks

[catman]

You didn't mention checking the brakes...