No. As long as you have the Adobe Flash plugin installed, you can use any modern web browser on a desktop or laptop machine.
As often as you'd like. You have complete control to make as many updates as often as you need. Need to change a booth assignment or the schedule 5 minutes before the show starts? Have at it!
For the desktop, all changes are seen immediately. For the mobile web app, the only change that requires a second step is to republish the floor plan for mobile. This requires clicking one button in your Event Control Panel.
If you have the Exhibitor Plus! tier turned on, you can invite each exhibitor to edit their own profile information through the access control manager. You can also limit the level of access each exhibitor has, just in case you don't want them to have access to every feature.
The system can work with any web browser that came out no earlier than 2008 and has Flash Player installed. As long as your Mac/Win/Linux machine has an up-to-date web browser, you'll be fine.
As you're editing, the floorplan auto-saves changes periodically. If you make a mistake in moving or splitting a booth, there is an undo button. We also have a "booth snapshots" feature that allows you to take a snapshot of all the current booth placements, colors, assignments, and sizes. At any point in the future you can revert to a previous layout. You can even save the current one before restoring a previous snapshot just in case you want to undo the switch back.
Good question. We do the initial setup and deliver the map at the point where you should only have to make edits. Clearly, the number of edits you'll need to make will dictate how much time, but the heavy-lifting has already been done by us.