Linking to sharepoint

Couple newby questions.
database is built like this,... I currently have all 15 of my tables linked
to sharepoint. 4 of the tables hold information that is linked together in
relationships such as an owner with his address owning multiple properties.
The remaining 11 tables handle information that rarly changes. built in
access 2007.
1. the "main table" has 1500 records and growing, would the database be
faster to work with if I only share the 4 tables that the info changes on?
2. Is there a way to automaticly back up these tables on a daily, or weekly
basis?
3. Is there a way to unlink the tables to sharepoint? I know you can take
them offline, but if I want to completly take them off sharepoint is that
posible?