Could someone please share ways to begin and end letters in Russian, and whether they are polite, business, or informal?

I know Дорогая and Привет. I assume the first is polite, and the second informal?

What is a business letter greeting, and what punctuation? ( In English, business letters can use Dear Sir/ Madame: )

What endings are appropriate for each kind of letter? What is the Russian equivalent of "Sincerely," or "Yours truly?"

I know "целую и обнимаю," certainly informal, and "Всего хорошего," which I think is polite. Leof used "С уважением и любовью," for an admired professor somewhere in this thread, would the "С уважением" be appropriate more generally?


Please give me some more choices, thanks!