I am an Indian citizen living and working in Germany. I'd like to apply for a Russian visa.
Do I need to go to the Russian embassy personally to apply for the tourist visa, or I can simply post the application stuff?
You do not need to go in person as long as your application is straightforward and you have an acceptable invitation. If the embassy decides your application is not straightforward they will ask you to make an appearance.
Visa for Russia are generally (depending on the city) handled by a visa center, not the embassy. When I applied for my visa for visiting Russia, I never went to the embassy. However, I had to visit (and leave my passport for a few days) a visa agent. You will almost certainly not be able to do this online, as they require your passport as well as some signed documents. A travel or visa agent can manage this for you, if not you need to visit the nearest visa center.
There is no requirement that you personally show up at the visa center, otherwise agents wouldn't be able to do it for you. Your best option would be to find the visa center that handles wherever in Germany you live and call them.