PS3 Check Out Failure

1. My PS3 client just shared an email from Authorize.net. Apparently they announced they are upgrading api.authorize.net to new security certificates later this month, which are signed using Security Hash Algorithm 2 (SHA-2) and 2048-bit signatures. These upgrades were already completed on secure.authorize.net in May of 2015. Looking at the AuthNet_PHP.php file it looks like PS3 uses secure.authorize.net, (I am not aware of any transactions failing). So can I assume that the gateway and PS3 solution should continue to work using SHA-2 signed certificates (i.e. api.authorize.net does not come into play with PS3.)?

2. In October 2015, due to Authorize.net to system updates, it will be possible to receive Authorize.Net IDs (Transaction ID, Batch ID, etc.) that are not in sequential order. Does PS3 have any functionality that expects Authorize.Net-generated IDs to be sequential? I do not see anything in the PS3 code that expects sequential IDs. Am I correct?

3. Authorize.net also will no longer allow a 10 character field limit on the Transaction ID. They are saying that if any solution (PS3 in this case) is required to define a character limit when storing any of their IDs, the limit should be no less than 20 characters. Is PS3 fine with more than 10 characters?

4. Authorize.net is switching to Akamai (third-party cloud network service) that routes and delivers Internet traffic.They recommend updating to new transaction URLs that are available now. The one that seems to apply to PS3 is https://secure2.authorize.net/gateway/transact.dll. The following line of code appears in the PS3 AuthNet_PHP.php file:
curl_setopt($ch, CURLOPT_URL,"https://" . ($reqArray[1][4] == 1 ? 'test' : 'secure') . ".authorize.net/gateway/transact.dll");
Can I just append a "2" after "secure"?

5. Finally, do any of the answers to the above change if I can convince my client to upgrade to PS4? Or should I wait for responsive, mobile friendly PS5? Any release dates for PS5?

Thanks very much for your help!
Robert