>>1. Is there any posibilities that will create problems in the existing tables in foxpro 2.6 for windows by the time of deployment of new application system written in visual foxpro 7.0

If I recall correctly 2.6 used the old FoxBase/dBaseIII table structures so 7.0 should be able to read a 2.6 table without any problems. I actually have never had any problems reading a table from an earlier version in a later version. But... If you modify the structure of the a 2.6 table in 7.0 you could run into some problems using the table in 2.6 afterwords. Same goes for including it in a database. 2.6 cannot read the 7.0 table structure.

2. What are the procedures of using a tables from foxpro 2.6 for windows to new application visual foxpro 7.0? If there is....

Same as any other table.

When upgrading an application, I usually create routines to convert the old tables into new tables. That way I can change the tables any way I want to in the new app and it won't effect the older application.