Is there a way to search the latest version of every file in TFS for a specific string or regex? This is probably the only thing I miss from Visual Source Safe...
If you install TFS 2008 PowerTools you will get a "Find in Source Control" action in the Team Explorer right click menu.
TFS2008 Power Tools
In my case, writing a small utility in C# helped. Links that helped me - http://pascallaurin42.blogspot.com/2012/05/tfs-queries-searching-in-all-files-of.html
How to list files of a team project using tfs api?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.TeamFoundation.Client;
using Microsoft.TeamFoundation.VersionControl.Client;
using Microsoft.TeamFoundation.Framework.Client;
using System.IO;
namespace TFSSearch
{
class Program
{
    static string[] textPatterns = new[] { "void main(", "exception", "RegisterScript" };  //Text to search
    static string[] filePatterns = new[] { "*.cs", "*.xml", "*.config", "*.asp", "*.aspx", "*.js", "*.htm", "*.html", 
                                           "*.vb", "*.asax", "*.ashx", "*.asmx", "*.ascx", "*.master", "*.svc"}; //file extensions
    static void Main(string[] args)
    {
        try
        {
            var tfs = TfsTeamProjectCollectionFactory
             .GetTeamProjectCollection(new Uri("http://{tfsserver}:8080/tfs/}")); // one some servers you also need to add collection path (if it not the default collection)
            tfs.EnsureAuthenticated();
            var versionControl = tfs.GetService<VersionControlServer>();
            StreamWriter outputFile = new StreamWriter(@"C:\Find.txt");
            var allProjs = versionControl.GetAllTeamProjects(true);
            foreach (var teamProj in allProjs)
            {
                foreach (var filePattern in filePatterns)
                {
                    var items = versionControl.GetItems(teamProj.ServerItem + "/" + filePattern, RecursionType.Full).Items
                                .Where(i => !i.ServerItem.Contains("_ReSharper"));  //skipping resharper stuff
                    foreach (var item in items)
                    {
                        List<string> lines = SearchInFile(item);
                        if (lines.Count > 0)
                        {
                            outputFile.WriteLine("FILE:" + item.ServerItem);
                            outputFile.WriteLine(lines.Count.ToString() + " occurence(s) found.");
                            outputFile.WriteLine();
                        }
                        foreach (string line in lines)
                        {
                            outputFile.WriteLine(line);
                        }
                        if (lines.Count > 0)
                        {
                            outputFile.WriteLine();
                        }
                    }
                }
                outputFile.Flush();
            }
        }
        catch (Exception e)
        {
            string ex = e.Message;
            Console.WriteLine("!!EXCEPTION: " + e.Message);
            Console.WriteLine("Continuing... ");
        }
        Console.WriteLine("========");
        Console.Read();
    }
    // Define other methods and classes here
    private static List<string> SearchInFile(Item file)
    {
        var result = new List<string>();
        try
        {
            var stream = new StreamReader(file.DownloadFile(), Encoding.Default);
            var line = stream.ReadLine();
            var lineIndex = 0;
            while (!stream.EndOfStream)
            {
                if (textPatterns.Any(p => line.IndexOf(p, StringComparison.OrdinalIgnoreCase) >= 0))
                    result.Add("=== Line " + lineIndex + ": " + line.Trim());
                line = stream.ReadLine();
                lineIndex++;
            }
        }
        catch (Exception e)
        {
            string ex = e.Message;
            Console.WriteLine("!!EXCEPTION: " + e.Message);
            Console.WriteLine("Continuing... ");
        }
        return result;
    }
}
}
Team Foundation Server 2015 (on-premises) and Visual Studio Team Services (cloud version) include built-in support for searching across all your code and work items.
You can do simple string searches like foo, boolean operations like foo OR bar or more complex language-specific things like class:WebRequest
You can read more about it here: https://www.visualstudio.com/en-us/docs/search/overview
Assuming you have Notepad++, an often-missed feature is 'Find in files', which is extremely fast and comes with filters, regular expressions, replace and all the N++ goodies.
This search for a file link explains how to find a file. I did have to muck around with the advice to make it work.
In the case of the cd command, I performed the cd command because I was looking for the tf.exe file. It was easier to just start from that directory verses adding the whole path. Now that I understand how to make this work, I'd use the absolute path in quotes.
In case of the tf search, I started at the root of the server with $/ and I searched for all files that ended with sql i.e. *.sql.  If you don't want to start at the root, then use "$/myproject/*.sql" instead.
Oh! This does not solve the search in file part of the question but my Google search brought me here to find files among other links.
This add-in claims to have the functionality that I believe you seek:
Team Foundation Sidekicks