Moving to Germany from Australia Questions:) (Berlin)

Hallo, alle miteinander!

I am migrating to Germany (Berlin) in Feb Protected content looking to make some new friends and connections :) So if your in Germany at this time please say Hi :)

I have some questions below regarding applying for work and was wondering for those who have migrated or even if you are a permanent resident could you help answering some of these?

1) I plan to move in February Protected content Berlin. Given I will still be under 30 I will most likely get the Working Holiday Visa, however this is only valid for 12 months. If was to gain successful employment could that be transferred to a resident permit? OR

Because of the bilateral agreement between Australia and Germany, I can stay for up to 90 days without a visa but I can't work, however use this time to find employment?

2) Should I apply for jobs in Berlin from Sydney? Like a 1 month before actually arriving? Or should I wait until I am there for better chances? Is there any harm in communicating with recruiters now to let them know that I will be in Berlin in February Protected content ?

3) When applying for a position, should I submit my Cover Letter & Resume in German? or both in German/English?

4) I will be undertaking a German languages course basic/intermediate before I leave, having achieved intermediate levels is this sufficient for gainful employment?

5) Do you know know of any large recruitment agencies in Germany specifically in the Facilities Management Sector?

Thank you all in advance :)

Eddy