Do we need to set the object to null to invoke the destructor?

Answer 1

It depends on if dispose method is available
If not you should set it to null. this way you keep low memory consumption and it also help the garbagecollector.
im not obsesive but i always try to code with a lot of "using" command.
And for the framework stuff use "dispose" for every thing as soon as posible.
something like never is the use of "redim"

Answer 2

No