Minimum: 250MB-3GB or 5%.
Recommended: 10%
A free Windows XP repair disk can be downloaded from Softonic, Tech Republic, Kioskia, Software Solution, Boot From CD, PC Support and Disk Internals.
The graphic.bmp file The Backup folder
What you actually want is a Windows recovery disk, you can buy one from Microsoft, or you can create one from an existing Windows system (though I don't remember how, try Googling "system restore disk creation"). Downloading a free disk is illegal under Micro$oft's terms, so you'd be hard-pressed to find a site that offers free Windows recovery disks.
nowhere
You can use the same method used in previous versions of Windows: Open the Windows Explorer (press Windows-E). Right-click on a disk or partition, and select "Properties", to check the free space.
Since I know longer have a windows 95 disk I can't say for sure but I think it is around 50M to at most 100M. If you have the disk package it should say or the upgrade screen will probably tell you if you have enough. This is an old system and there is better stuff out there unless you have an old computer you want for some reason.
A good way to free up disk space is to run the windows disk clean up utility by going to "start" and in the search bar type in disk cleanup. Run it and delete all of the files it asks you want to delete. Also you can run the Disk Defragmenter utility to move files around to better places on your computer. I would suggest to download CCleaner to clean the computer.
The short answer is - you can't ! Every copy of Windows software must be paid for, whether that's buying an upgrade from the version you're already using - or a complete install disk. There are no legal free downloads of Windows software !
Go to Control Panel and double click on the "C Drive' Icon. (Assuming C is the letter for your hard disk). Then on a free area inside the window, right click and select 'properties' then 'tools'. It should be there.
System and Maintenance
No, you shouldn't need a drivers disk besides the Windows 98 disk. It is however always better to do a fresh clean install rather than an upgrade as this just "overlays" your Windows 95 and there have been some problems with the upgrades. If the system asks you for a certain driver, you can alway go to Microsoft and download the needed driver for free.
The system requirements to installing a virtual Windows machine on a computer are simple - Any 64bit processor, at least 2Gb of free memory and 750Mb of free hard disk space.