The post you link to, http://meta.stackexchange.com/questions/2677/database-schema-documentation-for-the-public-data-dump-and-data-explorer/2678#2678Database schema documentation for the public data dump and SEDE, is the schema; so yes it does contain the schema. You can get column sizes from the Data Explorer if you want.
The fact that the files are
.002, etc. would imply that it's been split. Probably using 7-Zip's split functionality. You can either use 7-Zip to recombine them or use another tool such as HJSplit.