hi, just a few quick notes:
re. the 1st post, the change of a final acute to a grave isn’t a “loss” of accent. As Devine and Stephens explain it, the difference between an acute and a grave is that:
(a) the syll after an acute is on a lower pitch, whereas
(b) the syll after a grave is on a higher pitch.
so it’s not really a loss, it just signifies a different pitch pattern. for my summary of Devine and Stephens (i tried to simply the rules down into a technique of relative pitches), i can’t link on textkit anymore but:
(a) google “mhninaeide”
(b) add this filename to the end of my free website: GreekPitchModel.pdf
secondly, note you don’t accent *ἄνθ?ωπου (which breaks the law of limitation) but ἀνθ?ώπου. the final diphthong ου is definitely long for accentuation purposes. it’s the final αι and οι diphthongs which are short for accentuation purposes (except in the optative, adverbs like οἴκοι, &c.) it’s worth going through the probert accentuation exercises book once, i found it really helpful.
re. correption, i don’t believe this occurs in attic prose but i’m no expert, this is just based on what i’ve come across so far. i saw nothing on it in Threatte 1980, i think also i checked this in dionysius of hal’s scansion of attic prose (can’t confirm now, i don’t have my classics books here). also, if you’re interested in correption generally, i read an interesting book on correption statistics in homer: there are different frequencies in the dialogue and non-dialogue parts (Kelly 1990: for a quick summary, see my old Iliad A notes, note on line A.299).
one way to follow up this question on whether correption applies in prose would be to find a commentary on dionysius thrax… i remember that he says that ὅτ᾽ ἂν εἰς φωνῆεν μακ?ὸν λήγηι καὶ τὴν ἑξῆς ἔχηι ἀπὸ φωνήεντος ἀ?χομένην, the final syll of such a word is κοινὴ συλλαβή (i.e. it can scan long or short), however he doesn’t specify whether this only applies in homer (he gives a homeric e.g. after this) or in prose as well. a commentary might explain this further, giving e.g.s from elsewhere. i don’t have access to one but if you do, it’d be interesting to find out 
re. your question lucus on “the fusion of a final vowel and an initial vowel into one syllable”, this is called crasis. it doesn’t occur in all cases, you need to check the list relevant to the genre you’re reading:
(a) for attic prose, the best list i have is Threatte 1980 pgs 428 and following, showing how crasis worked in attic public and private texts after 480BC. my free website won’t let me upload my scan of the relevant pages, too big, but if you want i can email it to you,
(b) for attic poetry, see my iambic notes page 41 (my summary of sidgwick GVC),
(c) for sappho, see my sappho notes page 10 (my summary of a german grammar of sappho and alcaeus).
re. your final question, there are 5 sylls.
hope some of this helps, cheers, chad. 