Does English has other examples of English/German p->f alteration?

All languages exhibit sound substitutions. For example, the bible mentions a river named Pareth. For a while that river was called Firat, and now it is called Euphrates. Another example is the Hiddekel/Diglat/Tigris.

Your examples merely illustrate that English is descended from German. Students of language are advised to study Latin first because that gives them almost half of the vocabulary for most other European languages, and German gives part of the other half.

The High German consonant shift (aka second Germanic consonant shift ):
wikipedia