Subject: How does BCS theory explain superconductivity?

As I understand it, resistance in normal conductors is caused by nuclei in the 
material getting in the way of the flow of electrons.

As I understand BCS, as a superconducting material gets colder and colder, the 
electrons begin to pair up, and the lack of heat can't disrupt these pairs.  
I've read that this is similar to what happens in a superfluid.  In our case, 
pairs of electrons condense into one quantum state.  Is this because the 1/2 
integer spins of the electrons pair up and form bosons?

The second part of my question is that this pairing doesn't seem to solve our 
original problem.  The original problem isn't that our electrons are getting in 
each others way, it's that the nuclei are getting in the electrons way.  If I 
can't drive my car fast through a forest because there are too many trees in 
the way, a bigger motor doesn't fix anything.  How does BCS theory solve the 
problem of the nuclei?

Some explanations I've seen here say that there is an interaction between the 
lattice and the electrons and that the positively charged nuclei tug on the 
pairs of electrons as they move along.  It seems completely counterintuitive 
that an interaction between a massive nucleus and a tiny electron would result 
in the electrons trajectory being unchanged and the nucleus being moved 
instead.  If the electrons do form bosons, does it somehow effect their mass 
and how they interact with the nuclei?  

Re: How does BCS theory explain superconductivity?