1) You can bulk update the iteration of the test cases in the suite. To do so go to the Test Case tab in the suite editor and select multiple test cases. From there select all the test cases and above the table there's a "change execution properties" icon (looks a little like a spreadsheet with a run overlay). From there you can change the plan/milestone/configuration information for the test cases in the suite. FYI... This is a little different and a little easier in RQM 3.0. Because there's something new coming called Test Suite Execution Record and the planning information is in it.

2) Doing a bulk assignment of the adapter to use for the cases in the suite. Yes you can do this too. In the test suite run dialog you can select all the test cases you want to update. Then in the upper right corner there's an edit icon (pencil), that will allow you to do a bulk update of the adapter that a set of test cases will run on.

3) Modify the script arguments of multiple test scripts at once. You can't do this in 2.0 nor 3.0. But in 3.0 there's something new called execution variables. They are similar to script argument, but can be specified at different levels of the artifact hierarchy (script,case,suite). So you can modify the execution variables at the suite level and have that impact all the test cases in the suite. See RQM work item 31614 for more details.

4) Your last question relates to accessing the Test Environment parameter from within your RFT script. There is a way to do it, but it's not easy. It involves accessing a task.xml file that contains a URL to the execution work item in RQM. You would then have to use the RQM Web API to access that URL. Get back the XML for the work item and follow another URL to the Test Environment. Let me know if you want more info on that. In 3.0 you could use the execution variables to accomplish this.