As previously mentioned, I had some trouble getting the different visa. My short trips to Bangkok didn't make it easier as I always had to take my passport with me.
Nepal's never been an issue because I get it on arrival at the airport.
I was concerned about the Russian visa because they tightened the regulations for Germans recently. But with the support of my friend Sascha from Saint Petersburg I got a letter of invitation from a Russian travel agency with which it was straight forward.
The Chinese visa application center in Singapore insisted to get the original documents from the travel agency in China. FedEx needed 3 days longer than expected so there wasn't enough time left before I had to fly to Bangkok again (the second visit when I had to pick up the spare parts from the airport). To save valuable time I thought I can apply for it there. After 3 hours of queuing it turns out that the letter of invitation from China is only valid for an application in Singapore…once back there, I got it within one working day.
After the third visit to the High Commission of Pakistan in Singapore I eventually got the Pakistani visa. The whole process was really pain in the ass because they requested one more additional thing at every visit, e.g., when I brought the letter of invitation from a government registered Pakistani travel agency they asked for a copy of the passport of the owner of it to proof the genuineness of the document. How ridiculous is that? After some discussion I could convince them to check the registration number of the agency. Three days later I collected my Pakistani visa.
In the end, there wasn't enough time left to get the Indian (requires five working days, no urgent service) and Kazakh visa. So I'll have to apply for them on the way: the Indian one in Kathmandu and the Kazakh one in Urumqi.