well, that doesn’t sound too good… we updated the latest prebuild-sd-card-images to version 2.32. Maybe you start again with a fresh image. SD-Card expansion and wifi should work without any problems (as long as you start the expansion before the card is full). If you have a Pi 2 and not a Pi 3 with buil- in wifi, it might depend on your wifi-stick if anything is not working correct (e.g. disconnects). The kodi package is part of the image – no need to install anything.
So what are the major benefits of Max2Play: if you are only using you player for Kodi via HDMI and nothing else, you can take OpenELEC or some other distribution. If you want a flexible system with support of different players (Audioplayer, Multi-room Setup) and a lot of other things (see our features / plugins page) you won’t find a system that is this easy to configure. In other words, Kodi is just one little part of Max2Play.