Visitors Visa - Need to apply now or can we wait after this visit?

[usgcstatus]

My in-laws have a 5 yrs multiple entry visitor's visa that ends Sept 2009. They are planing to come in the month of June 2009 and stay here for 6 months. My questions are:

1) At the port of entry can they get a 6 month permit to stay or will it be limited to the duration of the visa ie Sept 2009?
2) If they are permitted to stay only till Sept 2009 and extension if filed later on be denied due to the duration of the visa ie Sept 2009?
3) Is it better to apply for a 5yr/10yr visa now and then come in the month of June 2009 instead of using the current valid visa until Sept 2009 for travel?

Any help much appreciated. Thank you!

 

[Triple Citizen]

A1: Visa validity has no connection to the duration of stay granted.
A2: Visa validity has no connection to EOS
A3: If the visa is still valid, why apply for a fresh one? One risks refusal.

1) At the port of entry can they get a 6 month permit to stay or will it be limited to the duration of the visa ie Sept 2009?
2) If they are permitted to stay only till Sept 2009 and extension if filed later on be denied due to the duration of the visa ie Sept 2009?
3) Is it better to apply for a 5yr/10yr visa now and then come in the month of June 2009 instead of using the current valid visa until Sept 2009 for travel?