Documents for UK standard visit visa (academic purposes)

I am a citizen of the Russian Federation. I work in Germany and plan to visit the UK for academic purposes (short visits). My employer and the host institution requested a long-term visa (2 years) for me.

My gross salary per year is in the letter from my employer and it is stated that my employer covers my expenses. I was told that it is better to provide bank statements as well.

1. Should the bank statements be signed by a bank authority and/or stamped? Or can I just print them from my online banking?
2. Unfortunately, my bank does not provide bank statements in English, only in German. But the bank statements are, more or less, tables of dates and numbers; there is my information at the beginning of the document, the names of the columns and the explanation/comments to/by whom a transaction was made. Should I provide the certified translation for the whole bank statement (more than 30 pages)?

I was also told that the more documents proving my need to go back home I provide, the better. Apart from my job, I have my family here. Should I provide my marriage certificate and birth certificates of my children or is it too much?

Thank you.