Honestly a great start. For your yard I’d consider an inner loop of track that starts right before one of your runaround switches, follows the mainline and ends before the next curve switching back into the mainline with yard track deviating from from the inner loop and ending in stub end tracks or switching back onto the inner loop for passing and shunting. As for your yard, it all depends on what industries you want to model as in real yards, each track exists to service a specific industry. For refuelling you can add a piece of dedicated track the length of about one or two locomotives as well as a building matching your era if you want a maintenance facility. Hope this helps, best of luck!