With StresStimulus, you can certainly simulate 1000 VUs, or much more, as there is no, per-se, limit on the number of VUs in the tool.
Now, on the request rate for individual VUs: StresStimulus emulates physical users with browsers that are cycling through their respective test scenarios. A physical browser, depending on its type, can send between 2 and 6 simultaneous requests to a host. StresStimulus will do the same. Once the number of pending requests for a VU reaches this limit (which is based on the type browser you select), StresStimulus temporary blocks this user until it receives responses from the server. Since StresStimulus does not have a control over the web server response rate, it does not have a full control over request rate.
Instead, StresStimulus has a mode where you can control test iteration rate. To issue iterations with certain frequency, in Multi-Test Cases section, set Delay between Iterations to Pacing, and then set the Minimum Iteration Duration, as shown below.
As far as emulating 10000 requests per second per VU, this load level is not realistic for a single physical user, and therefore StresStimulus will not support that, but you can generate the same load by selecting appropriate much larger number of virtual users.
As far as hardware and benchmarking, we can't give recommendation on specific hardware, as it will depend on many unknown to us factors, such as size and content of your test case, web server performance, etc. We have customers who simulate 1000 and more VU per server. One way to answer this question for your particular situation is to request a free unlimited VU trial and test it on physical machine or from Amazon EC2 instances.