While it's polite, IMO, to include some form of greeting or other pleasantries, in any kind of asynchronous communication medium, I do not want to wake up to (or come back from lunch to, or whatever) someone saying "Hey" or "Can I ask you something?" Chances are, by the time I've said "sure, go ahead", the person won't be there anymore, and then both of us just have to wait frustratingly.
>I really prefer people to warn me before dropping a bomb
Why? These "hi" or "are you there" or "can I ask a question" are useless to me. Also in the reverse role I find it useful to just type up my whole problem. Sometimes in the middle of typing it all up I will figure out a good solution and then just not send the message. Even if the person is not there to help you, you can always copy paste your message to someone else.
It depends, I mean in times of remote work it's good when the routine doesn't degrade to a purely mechanical exchange. Also it can be actually useful if people chit-chat about what they are doing which can lead to discussions and save time by cutting useless work. It's not ideal when people repeatedly ask me about a certain class of problems - terse or not - it's a disruption to my work.
(With dropping a bomb I also mean something like a larger/tedious amount of work)
