The .dat and .idx files are the data and index files for Ctree tables. They are created automatically, the first time they are needed, so they might not exist on all systems.
The OLFD001 and OLFD002 tables are the Online Field Definition tables used when you look up resources for tables, fields and windows from the Tools >> Resource Descriptions options in Microsoft Dynamics GP. They can be deleted and will be recreated next time Resource Descriptions is used.
The DYNAMICS and FAM, etc. tables are blank tables which are used for storing "Design Documents" when working with Modifier and Report Writer. The filename will match the filename of the appropriate dictionary, for example: DYNAMICS.DIC. This Dexterity functionality is not used any more, but has not been removed from the code, so the blank tables can be created when Modifier and/or Report Writer is used. They can be deleted.
The CN40102 & CN40103 tables are used by the Collections Management to store printer settings. When this functionality was first created there was a technical issue which prevented the binary data from being stored at the SQL level, so the printer settings were stored locally using Ctree tables. Named Printers had the same issue, but was changed once storing binary data in SQL tables from Dexterity was fixed. If you delete these, you will probably need to redefine the printer settings for collections management.
The sy50000 and sy50100 tables are used by the Table Import functionality built into the Runtime Engine to store the Definition IDs. Deleting these tables will mean that any Definition IDs will be lost.
I hope this information is useful.