Sometimes if the seal on the hoses is not good, when it cools down, and things contract, you'll get a small drip/leak. When warm can go away. Hoses may be cracked, too. Maybe new hose time? btw, I hate those plastic flush/fill things - they always end up leaking 'cuz they crack from over-tightening when people try to stop the leak! You can replace with a brass one, if you have to have it.
The missing hose is a breather tube the goes from the valve cover to Air Cleaner, as you've indicated. Yes, it can do damage, 'cuz you're gettin' unfiltered **** into the engine via the valve cover and carb! Get a hose!
btw, you don't have to use the Toyota hoses - you can go to NAPA and use the green-stripe stuff... I think ACE hardware may carry it, too.
Green-stripe is a Gates product. Here's the part #'s just in case you wanna do it, to get the correct sizes and some molded hoses.
Coolant Hose
Upper
Molded Coolant Hose 21660 Cut to fit
Flexible Coolant Hose (Standard) 25474
Lower - Eng. To Pipe; W/A.C.
Straight Coolant Hose (Standard) 24024 (9")
Lower - Eng. To Pipe; W/O A.C.
Molded Coolant Hose 20958 (B,C)
Lower - Pipe To Rad.; W/A.C.
Straight Coolant Hose (Standard) 24028 (14")
Lower - Pipe To Rad.; W/O A.C.
Molded Coolant Hose 20887
By Pass
Molded Coolant Hose 21222
Heater To Pipe-1
Straight Heater Hose (Standard) 28411 (5")
Pipe-1 To Pipe-2; W/Aux. Heater
Molded Heater Hose 18773
Pipe-2 To Eng.; W/Eng. Oil Cooler
Straight Heater Hose (Standard) 28411 (11")
Heater To Valve
90º Molded Heater Hose 28466 Cut to fit
Valve To Eng.
90º Molded Heater Hose 28467 Cut to fit
Eng. To Pipe-3; W/Aux. Heater
Straight Heater Hose (Standard) 28410 (9")
Pipe To Aux. Heater Pipe-1
90º Molded Heater Hose 28461 Cut to fit
Aux. Heater Pipe-1 To Aux. Heater
90º Molded Heater Hose 28460 Cut to fit
Aux. Heater To Aux. Heater Pipe-2
90º Molded Heater Hose 28460 Cut to fit
Aux. Heater Pipe-2 To Pipe
Straight Heater Hose (Standard) 28410 (5")