Nice Ranger to be sure. The small creaks and issues you mention I had with my Ranger 800. The suspension creak went away at about 70 hours and did not return. The vibration of the cargo box stayed but became tolerable as I used the machine more. It looks like Polaris has changed the style of seat between your Ranger an my 800, but it looks sharp. As for EPS, I had it on my Ranger and loved it. However, unless one does a lot of low speed work in tight spaces or wants to use a snowplow, EPS likely is a luxury. With either of those applications (I had both) it is almost a necessity. If you decide to do power steering down the road, you may wish to check with UNISTEER to see if they have developed a kit for your application. I put that on my new 825I Gator when I bought it because I knew I would be unhappy with not having power steering on the Gator after having it on the Ranger. FWIW, it works as well as the Polaris system, but was not cheap at around $900-$1K installed. I had a first generation Unisteer kit on a prior Gator and it helped but was fairly abrupt and clunky. They have really improved the system in this iteration. That all said, in most circumstances you will not likely miss not having EPS and if you do not need it, that money can either be saved or can be put to another accessory or attachment. You have a beautiful machine and I know you will really like using it.
John M