The first link for what you seek (i.e., "USGA voluntarily granted Martin a similar waiver") could be found here: The opinion of Justice Stevens himself:
FindLaw | Cases and Codes
The increase by one in the number of available slots? I dunno. Yet.
The concluding text of the opinion:
"Under the ADA's basic requirement that the need of a disabled person be evaluated on an individual basis, we have no doubt that allowing Martin to use a golf cart would not fundamentally alter the nature of petitioner's tournaments. As we have discussed, the purpose of the walking rule is to subject players to fatigue, which in turn may influence the outcome of tournaments. Even if the rule does serve that purpose, it is an uncontested finding of the District Court that Martin "easily endures greater fatigue even with a cart than his able-bodied competitors do by walking." 994 F. Supp., at 1252. The purpose of the walking rule is therefore not compromised in the slightest by allowing Martin to use a cart. A modification that provides an exception to a peripheral tournament rule without impairing its purpose cannot be said to "fundamentally alter" the tournament. What it can be said to do, on the other hand, is to allow Martin the chance to qualify for and compete in the athletic events petitioner offers to those members of the public who have the skill and desire to enter. That is exactly what the ADA requires.52 As a result, Martin's request for a waiver of the walking rule should have been granted.
The ADA admittedly imposes some administrative burdens on the operators of places of public accommodation that could be avoided by strictly adhering to general rules and policies that are entirely fair with respect to the able-bodied but that may indiscriminately preclude access by qualified persons with disabilities.53 But surely, in a case of this kind, Congress intended that an entity like the PGA not only give individualized attention to the handful of requests that it might receive from talented but disabled athletes for a modification or waiver of a rule to allow them access to the competition, but also carefully weigh the purpose, as well as the letter, of the rule before determining that no accommodation would be tolerable.
The judgment of the Court of Appeals is affirmed."
Looks to me like the Court is saying that allowing someone like Casey Martin to use a cart is
required udner the ADA, provided the golfer meets the requirements of the ADA.
Of course, each case must be determined on a case-by-case basis but the fundamental premise that a disabled, otherwise qualified professional golfer such as Casey Martin should be allowed to use a cart, wins out over the objections which were being put raised by the USGA.
