Samovars are interesting. The old ones had a vertical tube through the middle of the water tank. You would light charcoal inside the tube to heat the water. The tea itself was traditionally boiled separately until it was very strong, and then transferred to a pot. You would dilute the tea to your taste with hot water from the samovar, and put the pot on top of it to keep the tea warm.
Nowadays, of course, samovars contain electric heating elements and everyone uses teabags. It’s more common to just use electric kettles to heat the water, or to boil it on the hob, and let the tea steep inside a teapot.
I’ve seen Russians eat jam with tea, a tiny spoonful between each sip, but never stir it into their tea. It was another tradition to keep a sugar cube between your front teeth and sip your tea through it. I’ve seen old-timers who had black front teeth from doing this.
It’s common to put a slice of lemon in with your tea, but I don’t think I’ve ever seen a Russian drink tea with milk. At the institute I attended, there was always a tea break in the afternoon. The middle-aged woman who served the tea and snacks was very nice. When she found out I like milk in my tea, she started bringing big cans of sweetened condensed milk every day.