Help in indirect speech?

[Swth\r]

The locus is from Thucydides, 4.98

Τοσαῦτα τοῦ κή?υκος εἰπόντος οἱ Ἀθηναῖοι πέμψαντες κή?υκα [...] ἔφασαν ο?δέν [...] βλάψειν. [...] καὶ α?τοὶ, εἰ μὲν ?πὶ πλέον δυνηθῆναι τῆς ?κείνων κ?ατῆσαι, τοῦτ' ἂν ἔχειν· νῦν δὲ ?ν ᾧ μέ?ει εἰσίν, ἑκόντες εἶναι ὡς ?κ σφετέ?ου ο?κ ἀπιέναι.

The dependence of the whole speech of the Athenians lies on ἔφασαν.
My questions are:

1. why does the conditional clause have infinitive while the very next relative clause verb in indicative? Is it a short of attraction or something else?

2. Is the condition in direct speech "καὶ (ἡμεῖς) α?τοί, εἰ μὲν ?πὶ πλέον δυνηθεῖμεν τῆς ὑμετέ?ας (γῆς) κ?ατῆσαι, τοῦτ' (τὸ ἱε?ὸν) ἂν ἔχοιμεν" or "καὶ α?τοί, ?άν μὲν ?πὶ πλέον δυνηθῶμεν τῆς ὑμετέ?ας κ?ατῆσαι, τοῦτ' ἂν ἔχοιμεν". I suggest it is the first option (infinitive instead of optative)...

In the intermediate locus between the verb of dependence and the conditional sentence, three clauses having conjunctive occur, as also one clause having indicative. So my guess is that here the infinitive stands instead of optative. But I am afraid I need verification...

Thanks in advance for any answer!

[modus.irrealis]

[Swth\r]