προῆχε -- See Smyth 569-571:
569. Aspirated Second Perfects.—In many stems a final π or β changes to φ: a final κ or γ changes to χ. (φ and χ here imitate verb-stems in φ and χ, as τρέφω, ὀρύττω.)
κόπτω (κοπ-) cut κέκοφα, πέμπ-ω send πέπομφα, βλάπτω (βλαβ-) injure βέβλαφα, τρί_βω (τρι_β-) rub τέτρι^φα, φυλάττω (φυλακ-) guard -πεφύλαχα; τρέφ-ω (τρεφ-) nourish τέτροφα [nb: this seems to be an error in Smyth because the present stem already ends in an aspirate]; ὀρύττω (ὀρυχ-) dig ὀρώρυχα.
569 D. Hom. never aspirates π, β, κ, γ. Thus κεκοπώς = Att. κεκοφώς (κόπ-τ-ω cut). The aspirated perfect occurs once in Hdt. (ἐπεπόμφει 1. 85); but is unknown in Attic until the fifth century B.C. Soph. Tr. 1009 (ἀνατέτροφας) is the only example in tragedy.
570. Most such stems have a short vowel immediately before the final consonant; a long vowel precedes e.g.. in δείκ-νυ_-μι δέδειχα, κηρύ_ττω (κηρυ_κ-) -κεκηρυ_χα, πτήσσω (πτηκ-) ἔπτηχα. τέτριφα and τέθλιφα show ι^ in contrast to ι_ in the present (τρί_βω, θλί_βω). στέργω, λάμπω do not aspirate (ἔστοργα, poet. λέλαμπα).
571. The following verbs have aspirated second perfects: ἄγω, ἀλλάττω, ἀνοίγω, βλάπτω, δείκνυ_μι, διώκω (rare), θλί_βω, κηρύ_ττω, κλέπτω, κόπτω, λαγχάνω, λαμβάνω, λάπτω, λέγω collect, μάττω, μείγνυ_μι, πέμπω, πλέκω, πρά_ττω, πτήσσω, τάττω, τρέπω, τρί_βω, φέρω (ἐνήνοχα), φυλάττω. ἀνοίγω or ἀνοίγνυ_μι has two perfects: ἀνέῳχα and ἀνέῳγα. πρά_ττω do has πέπρα_γα have done and fare (well or ill), and (generally later) πέπρα_χα have done.
http://www.perseus.tufts.edu/hopper/tex ... ythp%3D571
why προσήκει was with an accusative. I suspect it is because it also serves as the subject of λογίζεσθαι.
No, προσήκει is impersonal. The subject of λογίζεσθαι.is τοὺς ὑπὲρ πόλεως καὶ νόμων βουλευομένους. λογίζεσθαι is a middle deponent (not passive) and takes a direct object, which is ἃ. The Greek doesn't map precisely onto English. The syntax is somewhat different.
ὥσπερ ἂν εἰ καθῆσθ᾽
why the ἂν εἰ are not simply combined to ἐάν.
This is not ἐάν - it's not a present indefinite/general condition (ἐάν + subjunctive in the protasis, present or future indicative in the apodosis), It's a contrary to fact condition. Here is the whole unit:
.. . . δεῖ πάντας ὑμᾶς τὸν αὐτὸν τρόπον ὥσπερ ἂν εἰ καθῆσθ᾽ ἐράνου πληρωταί, τὸν μὲν πειθόμενον τούτοις ὡς φέροντα τὴν τῆς σωτηρίας φορὰν πλήρη τῇ πατρίδι τιμᾶν καὶ ἐπαινεῖν, τὸν δ᾽ ἀπειθοῦντα κολάζειν.
Breaking it down, the complement of impersonal δεῖ is πάντας ὑμᾶς . . . τὸν μὲν πειθόμενον τούτοις ὡς φέροντα τὴν τῆς σωτηρίας φορὰν πλήρη τῇ πατρίδι τιμᾶν καὶ ἐπαινεῖν, τὸν δ᾽ ἀπειθοῦντα κολάζειν.
This sub-unit is adverbial: τὸν αὐτὸν τρόπον ὥσπερ ἂν εἰ καθῆσθ᾽ ἐράνου πληρωταί: "you must . . . in the same manner as if you were sitting"
This is a present contrary to fact condition, the normal form of which is protasis ει + imperfect, apodosis, αν + imperfect. Here we have ὥσπερ ἂν εἰ καθῆσθ᾽ ἐράνου πληρωταί with a skeletal apodosis consisting of ὥσπερ ἂν, and the protasis εἰ καθῆσθ᾽ ἐράνου πληρωταί (εἰ + imperfect).
ἂν, the skeletal apodosis, stands for something like ὥσπερ εποιειτε αν, or, more abundantly, ὥσπερ τὸν μὲν πειθόμενον καὶ φέροντα τὴν φορὰν
ετιματε αν καὶ
ἐπηινειτε αν, τὸν δ᾽ ἀπειθοῦντα
εκολαζετε αν. In other words, ἂν + imperfects.
It's just like English: "as [you would do] if you were sitting". "as if you were sitting".