Answers:
1. Payload is nakaka-nosebleed. Basta it's something na gagamitin mo in-terms sa pag babypass as something na pang "cloak" ng data na actual na sinesend and nirerecieve mo since freenet lang sya para kung baga legit yung nirerequest mong data kaya ka nagkakaroon at nakakapaload ng websites since nacoconvince ung server na legit ung source = which is the payload.
Examples ng payload sa http injector:
In terms of proxy naman, yun yung gagamitin as a "tunnel" para makadaan sa server (kay globe) para maka access ka ng mga requested data mo kahit wala ka namang privilege na dumaan kung baga sa gate ni globe.
2. VPN's are safe if you are just a casual internet user. As long as you take precautions in giving out your information plus secured ang device mo Good ka dyan. Actually mas secure nga pag VPN kasi you hide your real IP address so technically you are less prone to "häçkers" kung baga.
3. spys.ru's and all other free proxy sites are no assurance but as long as you are not a high-profile person (like Presidente ng Pilipinas) no harm naman sa pag gamit nyan
4. Not sure since di na kumakagat si Psiphon3 sakin. At more on kay http injector ako for pc.
5. Alien sakin si IHS HAHAHAHA di ko sya ginagamit

Proxifier naman hmm ginagamit ko sya using http proxy injector for pc. If you wanna learn how to use http injector i'll teach you ehe