inssider doesn't distribute a free version anymore but it's good advice. just find an alternative channel scanner
I use WiFi Analyser on my phone, works pretty well.
hiding the SSID is non-standard and should never be used. Usually the router broadcasts the name, so any clients can try to connect only when the hear the network in range. But if you hide it you force the client to constantly yell out on the off chance that the router is available and listening. This means not only at your own home, but at work, at school, at the park, and on your way everywhere. You're making your device literally yell out your home network name everywhere you go, instead of keeping it in one location where it actually exists if you just let the router broadcast the SSID. If any additional battery drain is noticeable at all, it'd be noticeable when you're nowhere near your network.
Exactly, and as a side affect the probes the devices send actually include the SSID of the hidden network, so people on the bus next to you could learn your network name (not that knowing the network name actually helps, which is why hiding it in the first place is pointless)
It's like putting a bit of tape over your house number, people still know you're there and can still workout who you are (But it doesn't mean they can unlock your door, analogies!)