Hi, Prometheus. Thanks for posting your translations. 
few points:
about how to translate the participle διαλεγόμενοι see above. you’ve treated it as a verb connected with ἐκάθιζον.
in the first paragraph, οὗτος ἐκείνῳ ἔλεγεν, literally meaning “this one (the bowman) said to that one (the peltast)”
can be translated as “the latter said to the former” but yours basically has the same meaning 
in the second paragraph, μέχρι here means until, they had spoken this way until (at which point they stopped and
told each other to be quiet) the general entered the place.
though it is possible to treat δεινὸς ἦν as referring to the situation, I meant more so to the general himself
being fearsome and thus (it would have been better to use ὥστε) they were afraid lest he be angry with them.
δι᾿ ὀλίγου ἐβουλεύοντο τίς αὐτῶν τῷ στρατηγῷ προσχωρήσει
καὶ μειλίξει αὐτόν (or ὅστις…προσχωρήσοι…μειλίξοι)
here the medial form of βουλεύω means “deliberate with each other, consider” and can take an indirect question.
you have the question first in its original form (albeit with changed pronoun), and then, in the parenthesis you have the
oblique way of writing it with no change of meaning: a) ὄστις instead of τίς, b)since the governing verb is past tense
(they considered who would…), the verb in the subordinate clause, that is the indirect question, can be written
as the equivalent optative. if the original verb is in future indicative, we turn it to future optative (as I’ve learned,
its only use is in indirect questions/statements).
μειλίττω = to appease; med. to grow calm, be soothed.
“They deliberated on who of them would (originally ‘will’) approach the general and appease him.”
then finally, the bowman τολμήσας [LSJ. τολμάω in part. he took courage] meaning they kept deliberating until
the bowman took the initiative:
“The bowman, nerving himself (after he had nerved himself), approached the general
of his own will (ἑκών) and said…”
Again, I really appreciate your replies and hope it’s a good enough exercise for all of us.
If I’m mistaken in something, please correct me.