Was x Been x Studied x Have studied:

Se a ação não terminou, deve-se usar o present perfect (I have lived). O simple past (I lived) é usado para ações iniciadas e concluídas no passado.

In sentence # 5 - "I have studied" doesn't mean the action didn't end, it actually ended (you finished the course) why then the "have studeid"? Because the action is still relevant to the present.
You studied to hone skills to move you forward and make your job easier at the very moment you are saying that, hence the "have" before "verb".

I agree with Luiz, but language rules have some 'shades of gray', when we send an email the system informs "the emails has been sent.", so the event has ended, but it still relevant to us, hence the "has sent" (has = have applied to third person singular). Outside that, the rule previously presented is okay.

Now the sentence "I have studied in London last year and I still live there" deserves an aside note. It's that if you are in London you can't say that.

This caught my eye, but then it could be that you are traveling and staying for a week in another place in England or the UK, so you could refer to London as 'there".

The pair "I have been to London" vs "I have been in London":
I have been to - mosf of the time you mean the person took a trip to London, and don't necessarily imply he or she is still there. I have been in London - suggests the persons is not in London, but was there at some point in the past, and that did a stint (lived for some time) in London.
If the person is in London, then "here". Beware the contexts, loose sentences sometimes can't be 'transferred' to others situations. Just saying!

As for "i have studied" vs "I studied" would be "in the mind of the beholder", if the person is talking and "feels" that the course is relevant right now then "has studied". If it's just making small talk, for instance, the "I studied" would suffice.