I'm sure I'm a little late responding. I could be wrong, but that looks like an older bow. Nothing wrong with that if its in good condition, and it fits you.
I'm not sure how to change the draw length on that particular bow. Some you change cams, some have adjustment pins on the cams and other use modules.
You may, or may not be able to get parts for it.
Whichever bow you get if its used, make sure parts are still available for it.
Otherwise, if you break a limb or need to replace a cam, and can't get the parts, you just wasted money on something you can't use or sell.
If the bow is in sound condition, I would take it to a reputable archery shop to have it tuned, and have good strings and cables installed.
Winners Choice are great, and hold up well. IIRC the last set I got 2 years ago were about 75 dollars. The last thing you want to have happen, is to draw back a compound bow and have the string come apart on you.
I was going to send you a p.m , but yours aren't set up. I suggest going to ArcheryTalk.com Its a great archery forum, and
there are lots of bows listed for sale. You can find some great buys on bows that are only 1 or 2 years old, because a lot of people on there buy a new bow every year.