The FP2K server extensions enable the web server to support features of FP2K used by SF2K webs. If you had a PWS installed when you installed FrontPage 2000, it added the FP2K extensions to your PWS. However, if you reinstalled or upgraded your PWS to a newer version after installing FP2K, you may have to reinstall the extensions. More info.
StoreFront 2000 requires a Data Source Name (DSN) be set up on your PWS using the ODBC Data Sources applet in the Windows Control Panel. The DSN is, just as it says, a name pointing to a data source (in this case a database) located on your system. The DSN will be set to point to the SF2K database which is created by default in the fpdb folder of your SF2K web.
Note that the DSN's name is not the same as the name of the database. They can and usually should be different. Thus, a DSN could be named "mystore" while the SF2K database could be the default name of "storefront.mdb" or changed to "store.mdb" or anything else legal.
Unlike earlier versions of SF, SF2K requires more than just a DSN string be edited in the global.asa file - with the web open in FP2K you must goto Tools>Web Settings>Database and select the system DSN you setup. This actually rewrites the global.asa with the correct database connection information.
There is what is called a "short" global.asa in the SSL folder, which only needs the DSN name edited in it, for most SF2K installations - this only becomes active when you publish to a live host. More info.
If you are running Windows 95 or 98, this component is not absolutely required on your local development computer to create and maintain StoreFront 2000 web sites. It is required if you are running Windows 2000 Professional. It also must be installed on a live SF2K web site on the remote, host server, in order to correctly use SF2K's Remote Administration and Product & Inventory Management features. It is part of the security of your StoreFront database, including the credit card information stored there with your customers' orders.
On a local development system, security is not an issue, normally. You can install MSADC on a local PWS under Windows 95 or 98, but I don't find it really necessary. More info.
To fully test a StoreFront web on your local computer with the PWS, you will need an ASP E-mail component installed on the PWS and be connected to the Internet to reach your e-mail server. Depending on which e-mail component your live host site uses, you might be able to download a copy of the component for local use. If you can't or don't want to do this, there is a trick you can do to avoid getting errors when you complete test orders due to the lack of an e-mail component.