No.251
It's all implied, yes. Part of the Russian charm, however, is the extent to which personal relationships are ultimately explored. Tolstoy and Turgenev do this as well.
No.252
It makes me cry T.T
No.261
Michael is Mike who is Mikey who is Misha.
It's not that complicated. It could be worse like Robert who is Bob who is Bill who is Rob who is Bert who is Bobby who is Robin. Look diminutives, it's not hard.
No.278
Russia just has a really unique naming system with lots of variants.
https://en.wikipedia.org/wiki/Eastern_Slavic_naming_customs