Which law applies?

German law always applies to the divorce procedure itself and also to support / alimony law (Unterhaltsrecht).

This may be different for the sharing of marital gains (Güterrecht). For marriages before 29. January 2019 usually the joint citizenship of the spouses is decisive for the applicable law on marital gains.

What are the consequences?

Divorces in Germany are always handled by family courts. Divorces of foreigners in an embassy (on German soil) are not recognized by German authorities. This may play a role if the foreigners stay in Germany after an "embassy divorce". They are still considered as spouses by the German authorities.

A year of separation is required before the marriage can be divorced.

You may apply for the divorce before the separation year is over, but first consult your lawyer about that, as there can be financial risks involved.

The court does not automatically rule on any of the typical claims in the context of a separation. If you want a regulation on spouse support or on the sharing of marital assets, your lawyer has to specifically apply for that. Separate court procedures on these matters (after the divorce) only make sense, if a fast divorce appears to be necessary. 

You also may apply for an equalization of pensions (Versorgungsausglich) that have been acquired in Germany.