Hey, it seems like you want this menu to be the center of all the game interactions in your server, so i think im a good candidate for this job because i have experience making custom FiveM menus. I know you wrote Lua as a required skill but I have experience in C# with a FiveM library called MenuAPI, which is makes really high quality menus that are easy to modify and customize. In fact if you've ever used vMenu, probably the most popular FiveM menu, it's made with MenuAPI!
If you really want I can use raw HTML, CSS, and JS and make a NUI based menu, but i think MenuAPI will be a much better experience for your developers and players. Time frame will depend on what features you want in the menu. If you have any questions or want to see other work i've done, you can message me on freelancer or on discord, abhi#4158 :)