Ok...I solved. I don't know if this is the right way but it function properly.

I've done a custom extension method to get DataType KVP The result is a Dictionary

using System.Collections.Generic;
using System.Linq;
using Umbraco.Core.Models;
using Umbraco.Core.PropertyEditors;
using Umbraco.Web.Composing;

namespace AFStarterKit.AFBusinessLogic
{
    /// <summary>
    /// Umbraco DataType Extension
    /// </summary>
    public static class DataTypeExtension
    {
        /// <summary>
        /// Get KVP By DataType Name
        /// </summary>
        /// <param name="dataTypeName"></param>
        /// <param name="keyId">0</param>
        /// <returns>List of KVP</returns>
        public static Dictionary<int, string> GetKVPByDataTypeName(string dataTypeName, int keyId = 0)
        {
            return DataTypeListContent(Current.Services.DataTypeService.GetDataType(dataTypeName), keyId);
        }

        /// <summary>
        /// Get KVP By DataType Id
        /// </summary>
        /// <param name="dataTypeId"></param>
        /// <param name="keyId">0</param>
        /// <returns>List of KVP</returns>
        public static Dictionary<int, string> GetKVPByDataTypeId(int dataTypeId, int keyId = 0)
        {
            return DataTypeListContent(Current.Services.DataTypeService.GetDataType(dataTypeId), keyId);
        }

        /// <summary>
        /// DataType List Content
        /// </summary>
        /// <param name="dataTypeList"></param>
        /// <param name="keyId"></param>
        /// <returns>List of KVP</returns>
        private static Dictionary<int, string> DataTypeListContent(IDataType dataTypeList, int keyId)
        {
            Dictionary<int, string> dataTypeValues = new Dictionary<int, string>();

            if (dataTypeList != null)
            {
                var kvpList = (ValueListConfiguration)dataTypeList.Configuration;

                if (kvpList != null && kvpList.Items != null)
                {
                    foreach (var kvp in kvpList.Items)
                    {
                        dataTypeValues.Add(kvp.Id, kvp.Value);
                    }
                }

                if (keyId > 0)
                {
                    return dataTypeValues.Where(kvp => kvp.Key == keyId).ToDictionary(p => p.Key, p => p.Value);
                }

                return dataTypeValues;
            }

            return null;
        }
    }
}

So...I now can retrieve the KVP filtered by category/ies

// DataType Name
string dataTypeName = "ChkbList-Categories";

// Request param
int keyId = (!string.IsNullOrEmpty(Request["cat"])) ? int.Parse(Request["cat"].ToString()) : 0;

// Get KVP By DataType Name (filtered)
var dataTypeKVP = AFStarterKit.AFBusinessLogic.DataTypeExtension.GetKVPByDataTypeName(dataTypeName, keyId);

Now I will work to simplify the code (if possible)...but in the meantime, I hope this can help those with the same need