Moreyball,
The NBA doesn't have a firm salary cap,it has some stretch to it. There is a seperate Luxury Tax that is designed to keep the stretching in check. But to keep teams from gaming the CBA,there is some fuzzy math that only applies in the Off-Season that most reporters-and fans-forget or don't know.
(Edit add.) The Lux Tax has nothing to do w/the ability to sign players. It's simply a tax to make it financially painful to spend too much money on salaries.
Bird Rights allow a team to re-sign its' own FAs regardless of the team's cap situation,BUT the player still counts towards the salary cap at his last yr's salary until he is either signed to a new contract or has his rights renounced by the team.(Bird Rights also allow a team to give bigger raises and a longer deal than other teams can,so giving up the Bird Rights eliminates the financial edge a team has w/it's own FAs.)
For figuring out the salary cap number a team has for the Off-Season not only are salaries included,but also "cap holds" that include the slotted salaries of any unsigned First Rd picks,traded player exceptions,the last yr of any of the team's own FAs,a charge for having less than 12 players(equivalent to a rookie min contract),the MLE and Bi-Annual Exception and a huge cap hold of between 200 and 300% of the qualifying salary for rookies in last yr of a First Rd deal.( For example,if the Rockets make a Qualifying Offer to Lowry for the $2.9mil,he actually counts as $8.7mil against the cap,until he's signed or the team renounces his rights.)
Exceptions are by definition an exception to the salary cap,you can either have an Exception or salary cap room,not both. Teams can always renounce their Exceptions to get more cap room,but once renounced,they're gone.
In the Magic's deal w/Gortat,they were above the Salary Cap to begin w/. So long as they have Bird Rights they can re-sign their own FAs. Dallas made a full MLE offer to Gortat and the Magic used their right to match their own Resticted FA and technically re-signed him using their Bird Rights. Note that if Gortat had been an Unrestricted FA,the Magic would not have had the right to match and Gortat would be in Dallas now.
In your first Scola question,yes,but Scola's last salary would still count towards the salary cap.
For your second Scola question,yes,but again,the last yr of Scola's contract still counts towards salary cap.
Say the Rockets and Scola agree on a new contract at $6mil/yr. But they want some room to sign a FA. They can delay signing Scola til after the FA is signed and then sign Scola w/Bird Rights as you've suggested. But Scola's 2009 salary of $3.284mil still counts towards the cap,so the Rockets actually created only $2.72mil in cap room for signing FAs.
