Hi Merlino
We are also in the same situation as you, and about to lodge our 887 application in the next few weeks and for evidence we are going to provide;
Proof of living: Tenancy agreement, car rego and bills from both addresses where we have lived
Proof of Employment: work contract, a few pay slips from the last 2 years and end of year tax forms,
I dont think you need a letter from your employer, last mnths pay slip would prob be enough to prove that you are still working for the same people if you have your job contract stating the date you started working for them.
It would be good to hear how your going as I havent seen anyone else who is apply for 887 at the moment, and it would be interesting to see how long applications are taking to get granted,
Good luck with it all