Hardy is making quite a lot of unusual word choices. In some cases I think he is cheating a bit, choosing things that are not quite the right words in order to fit the rhyme and the meter. A lot of the words are old-fashioned, 19th-century, poetic, flowery. "Anon" is NOT the abbreviation "anon." It is a word in itself meaning "at a later time." You see it in writing like Shakespeare. "Sweet sir, sit; I'll be with you anon" means "I'll be with you later." Yes, "projecting" means "transferring," but with a sense of pushing forward. I don't think "oblivion" means "forgetting." I think Hardy is talking about the common phenomenon of traits skipping generations; a man's son may not look much like him, but then the grandson may surprise everyone by looking exactly like his grandfather. "Durance" just means "a long period of time." "The human span of durance" just means "lifetime." I don't think "despise" means "hate." It means something more like "ignore" or "not care about." Imagine time were some kind of person, an enemy, old Demon Time. "Flesh perishes," time is the enemy of our bodies, our bodies only last a lifetime. When old Demon Time issues the "call to die," the body obeys that call, the flesh perishes. But "the family face" can say to old Demon Time "Hah! You are nothing to me. You do not matter. I scorn you. I have contempt for you. You may kill the body, but I, the family face, will keep reappearing over and over again. You can issue the 'call to die' and the body will heed that call, but I will ignore it."

1) means "forever"

4) means certain characteristics continue in both mankind and in families, even though an individual person does not live long

3) means "eternity"

2)yes