1) Our suggestion for installing Version 2018 is to uninstall any 2015-2017 version of GPSeismic that might be already installed. While you can install Version 2018 with an existing installation, there are problems in doing so. The first is that the QuikLaunch program which provides the popup access to applications in the status bar of your PC will continue to access Version 2017, not 2018. The second is that if you later uninstall a previous version, this uninstall will remove the GPSeismic service which is a required program that is run in the background of your system. You can fix this by re-running the Version 2018 installation and choosing 'Repair'.
2) There will be two dialogs. The first will install prerequisite Microsoft components. The second will install the GPSeismic libraries and executables. The second dialog will also prompt for the location of the program and data folders and provide options for installing just the program files and/or the sample data. Once the installation is complete, the user closes both dialogs.
3) Version 2014.3 MDB and earlier can be left on your system. There are no know conflicts with Version 2018.