καὶ—and so, giving the result, as often.
σφετέρων—ἑαυτοῦ would be more correct here and in c. 3.4; but the whole side is meant.
ἐς χιλίους—direct object of ἀναλαβών. A prep. and its case may stand for subj. or obj. of a verb.
τοὺς πάντας—πᾶς preceded by the art. gives the sum total. Cf. II. 7 ἐς τὸν πάντα ἀριθμόν. (The Sicels were always a number of isolated atoms except only when united under Ducetius and to some extent under Archonides.)