Does filtering by MAC address and turning off SSID broadcast help secure my network ?
Filtering by MAC address can delay attacks sligtly, however, since MAC addresses can be easily spoofed it does not provide significant advantage against a determined attack.
Turning off SSID broadcast will not prevent an attacker from sniffing it, as it is still broadcast during client authentication. Tools like Kismet and airodump-ng can usually find the correct SSID within minutes.
The way to significantly improve your wireless network security is by using a modern, WPA2-AES (or WPA2-PSK with very strong passphrase) encryption standard.