Re: Respectful plural forms
1&2 In modern Russian the only respectful form is the second plural "Вы"
The Korovyev's use of the 3d person plural is out-of-dated, it was common in 18-19 centuries among servants when they were talking about their masters (both pronouns and verbs) : "Барыня чай пьют", "Господин полковник уехали" etc. But it wasn't at all literary or normal language and was considered a language of the lower class people. Bulgakov uses this language on purpose, to emphasize Korovyеv'v buffonary.