pop the win98 cd in (although you really should use something better like winme, which still sucks, or win2k, which is the best), when setup starts, reformat the hard drive and install the operating system - everything will be cleared out.
No, microsoft won't have it because a boot disk is something you're supposed to have when you buy the software, and microsoft sucks like that. However, with the help of google you should be able to find copies of bootdisks on the internet, including freeware varieties like dr. boot disk which comes in handy from time to time.
If the laptop is relatively new you can boot from CD as I stated above. You may need to go into bios settings (hit delete on startup) and see if it's possible to boot from CD. No bootdisk required.
you need to make a boot disk then. you can do it somewhere from within the control panel. i have not made one in years i cant remember how to do it, just look around the control panel and somewhere in there theres an option to create a system disk. that is what you need to do (you will need the windows cd to do this though)