Use static class in ASP.NET Web API

I am posting this question using an automatic translation.
Please forgive any grammatical errors.

I have built an application using the .NET framework and the ASP.net Web API.
I have split the virtual path for each customer region within a site running on IIS and copied the same binary to run as separate applications.
The applications run in the same application pool.

Recently, some customers have been making a very large number of requests in a matter of minutes.
(I suspect a glitch in the system on the customer’s end).
I am thinking of adding a static class to my current application that keeps track of the number of requests per customer in a given time period and blocks them if the threshold is exceeded.
From past StackOverFlow articles I have found that "information in the static class is lost if the application pool is recycled", but I have determined that this is not a problem in this case.
For my purposes, I only need to be able to retain information for a few minutes.

However, I still have a few questions that I can’t find answers to, so I’d like to ask you all a few questions.

1. Even if the same binary is running in the same application pool, will the static class information be kept separately for different applications?

2. Will the static constructor of a static class be executed even after the application pool is recycled?

3. Is there a problem if I reference a field in Global.asax from within a static class?

4. Is there a problem with referencing the contents of web.config from within a static class?

Attached below is the source of my experimental implementation.
I plan to call the static method "ExcessiveRequestCheck.isExcessiveRequest" of this static class after the Web API receives the request and identifies the user ID.

Any advice would be sincerely appreciated.

P.S.
I understand that this approach does not work well in a load balancing environment. Currently my system only runs on one virtual machine. If you are moving to the cloud or deploying a load balancer, you will probably need a different approach than this one.

public static class ExcessiveRequestCheck
{
    private static Dictionary<string, ExcessiveRequestInfo> dicExcessiveRequestCheckInfo = new Dictionary<string, ExcessiveRequestInfo>();
    private static object initLock = new object();
    private static object dicExcessiveRequestCheckInfoLock = new object();

    //If possible, I want this process to be a static constructor
    public static Dictionary<int, int> dicExcessiveRequestSkipConditions
    {
        get
        {
            lock (initLock)
            {
                if (ExcessiveRequestCheck._dicExcessiveRequestSkipConditions == null)
                {
                    //if possible, I want to set this value from Web.config.
                    ExcessiveRequestCheck._dicExcessiveRequestSkipConditions = new Dictionary<int, int>() {
                        { 5, 3 }, { 15, 5 }, { 45, 10 }, { 120, 20 }
                    };
                }
                return ExcessiveRequestCheck._dicExcessiveRequestSkipConditions;
            }
        }
    }
    private static Dictionary<int, int> _dicExcessiveRequestSkipConditions = null;

    public const int BUFFER_CLEAR_MINUTES = 5;

    public static bool isExcessiveRequest(string userId)
    {
        ExcessiveRequestCheck.refreshExcessiveRequestCheckInfo();
        lock (ExcessiveRequestCheck.dicExcessiveRequestCheckInfoLock)
        {
            if (ExcessiveRequestCheck.dicExcessiveRequestCheckInfo.ContainsKey(userId) == false)
            {
                ExcessiveRequestCheck.dicExcessiveRequestCheckInfo.Add(userId, new ExcessiveRequestInfo() { countRequest = 1 });
                return false;
            }

            bool doSkip = false;
            ExcessiveRequestCheck.dicExcessiveRequestCheckInfo[userId].countRequest++;
            foreach (KeyValuePair<int, int> pair in ExcessiveRequestCheck.dicExcessiveRequestSkipConditions)
            {
                if (ExcessiveRequestCheck.dicExcessiveRequestCheckInfo[userId].lastRequesttTime.AddSeconds(pair.Key) > DateTime.Now)
                {
                    if (ExcessiveRequestCheck.dicExcessiveRequestCheckInfo[userId].countRequest > pair.Value)
                    {
                        ExcessiveRequestCheck.dicExcessiveRequestCheckInfo[userId].wasRequestSkip = true;
                        doSkip = true;
                    }
                }
            }
            ExcessiveRequestCheck.dicExcessiveRequestCheckInfo[userId].lastRequesttTime = DateTime.Now;

            return doSkip;
        }
    }

    public static void refreshExcessiveRequestCheckInfo()
    {
        lock (ExcessiveRequestCheck.dicExcessiveRequestCheckInfoLock)
        {
            var keyList = ExcessiveRequestCheck.dicExcessiveRequestCheckInfo.Keys;
            foreach (string key in keyList)
            {
                if (ExcessiveRequestCheck.dicExcessiveRequestCheckInfo.ContainsKey(key))
                {
                    var value = ExcessiveRequestCheck.dicExcessiveRequestCheckInfo[key];
                    if (value.lastRequesttTime.AddMinutes(BUFFER_CLEAR_MINUTES) < DateTime.Now)
                    {
                        if (value.wasRequestSkip)
                        {
                            //this NLog instance was created in Global.asax.cs
                            WebApiApplication.logger.Fatal("skip request! user id=" + key);
                        }
                        ExcessiveRequestCheck.dicExcessiveRequestCheckInfo.Remove(key);
                    }
                }
            }
        }
    }
}

class ExcessiveRequestInfo
{
    public DateTime requestStartTime { get; set; } = DateTime.Now;
    public DateTime lastRequesttTime { get; set; } = DateTime.Now;
    public int countRequest { get; set; } = 0;
    public bool wasRequestSkip { get; set; } = false;
}