As a result of a /d/ → /ð/ shift, fæder became father, hider became hither and togædere became together, giving us our modern English forms.

However, I know that murder and burden have archaic forms- murther and burthen. This means a shift from /ð/ → /d/ also happened, doesn't it?

The High German Consonant Shift turned /ð/ →/d/, a change that affects modern German and Dutch. The English that and Icelandic það versus the German das highlight this change, but it also went the other way- German tot versus English dead.

My questions:

1.) When did this consonant shift happen in English? Etymonline mentions 12c.

2.) What are some more examples of the /ð/ → /d/ in English words?

3.) How is the shift mirrored in other Germanic languages?