Now this man (Houtos men oun). Note men oun again without a corresponding de as in Act 1:6. Act 1:18, Act 1:19 are a long parenthesis of Luke by way of explanation of the fate of Judas. In Act 1:20 Peter resumes and quotes the scripture to which he referred in Act 1:16.
Obtained (ektēsato). First aorist middle indicative of ktaomai, to acquire, only in the middle, to get for oneself. With the covenant money for the betrayal, acquired it indirectly apparently according to Mat 26:14-16; Mat 27:3-8 which see.
Falling headlong (prēnēs genomenos). Attic form usually pranēs. The word means, not “headlong,” but “flat on the face” as opposed to huptios on the back (Hackett). Hackett observes that the place suits admirably the idea that Judas hung himself (Mat 27:5) and, the rope breaking, fell flat on his face and burst asunder in the midst (elakēsen mesos). First aorist active indicative of laskō old verb (here only in the N.T.), to clang, to crack, to crash, like a falling tree. Aristophanes uses it of crashing bones. Mesos is predicate nominative referring to Judas.
Gushed out (exechuthē). First aorist passive indicative of ekcheō, to pour out.