Mike - have you looked up the word καταστήσω in a New Testament Greek lexicon? Even in the Beginner's Forum, I would think that should be the first step. What lexicons do you have access to?
The dictionary form of καταστήσω is καθίστημι, which is used 21 times in the New Testament. You ask why καταστήσω appears only 2 times, it does not usually appear in the 1st person future tense. Do you know how to find the dictionary form of a verb when it appears in running text? In the short run, you use software as a crutch, e.g. by reading your text at http://www.laparola.net/greco/
, and you should really do that and look up the meaning in a lexicon before starting a thread here.
Here's Abbott-Smith's definition of the word. Note that it refers to your verse in definition #2:
καθ-ίστημι (and καθιστάνω, Ac 17:15), [in LXX for פָּקַד, קוּם, שׂוּם, etc., 24 words in all* ;]
1. (a) to set down;
(b) to bring down to a place (Hom., Xen., al.; II Ch 28:15, I Ki 5:3): Ac 17:15.
2. to set in order, appoint, make, constitute: Tit 1:5, II Pe 1:8; c. dupl. acc, κριτήν, Lk 12:14; ἡγούμενον, Ac 7:10; ἄρχοντα, Ac 7:27, 35 (LXX); ἀρχιερεῖς, He 7:28; seq. ἐπί, c. gen., Mt 24:45 25:21, 23, Lk 12:42, Ac 6:3; id. c. dat., Mt 24:47, Lk 12:44; id. c. acc, He 2:7 (LXX) (WH, R, mg. omit); pass. (v. Mayor, Ja., 115 f.), Ro 5:19, Ja 3:6 4:4; seq. εἰς c. inf., He 8:3; τὰ πρὸς τ. θεόν, He 5:1 (cf. ἀντι-, ἀπο-καθίστημι).
I hope this helps, but I also think that you need to get to where you can identify the dictionary form of a verb and look it up in a lexicon. In the short run you can use software to help, but as long as you need to do that, your reading skills will be very limited.
ἐξίσταντο δὲ πάντες καὶ διηποροῦντο, ἄλλος πρὸς ἄλλον λέγοντες, τί θέλει τοῦτο εἶναι;