What is the current version of HMWP you have installed in your site. You should be able to update it from your site’s backed (make sure that you have entered your purchase code in HMWP settings). Also, you can download the latest version (6.0.1) from your Envato Panel.
1) Yes, you’ll need to manually upload it replacing the previous plugin files/folders. It won’t affect your current plugin settings.
2) To check if it’s conflict with HMWP, please deactivate HMWP plugin and then check. The HMWP settings will be retained. Also it’s recommended to keep a backup of HMWP settings by clicking on “export current settings” button (Start tab) and save it in a text file.