First, I will do a rough translation for you;
“To love is to spend your whole life dedicating yourself to the loved one.”
Amor is a noun, it's the feeling of affection for someone/something; while amar means “to love”, it's a verb, the act of loving someone/something.
Yes, ser + fazer is a common occurrence, you might want to take a look at Portuguese non-finite verbs, in this case impersonal non-finite (Infinitivo Impessoal). Yes, it is a difficult topic to get a good grasp of, even linguists have a hard time with them. That's not a reason to give up, of course. :)
Estar fazendo is the same thing, it's a non-finite verb called gerundive.