Can we apply for the EIDL, take advantage of the $10K grant, then decline the EIDL loan if we decide to go with the PPP?

Not everyone will get 10 K grant. My understanding is you will get $1000 per employee.  Yes you can decline the EIDL alone

We do not believe the grant is exclusive with needing to close on EIDL. We have also heard you may be able to fund with EIDL and refinance with PPP

The code does indicate you can refinance the EIDL with a PPP. 
 

and yes, they’re doing $1,000 per employee