newbie question about the MagSafe charger

[bj097]

Is Apple's MagSafe charger the only charger that is recommended to charge iPhone 12 or above? Is there any reputable non-Apple alternative? I don't mind paying less for alternatives and taking risk if the risk isn't high

Second question: In the official site it is recommended to use with 20W USB-C Power Adapter (sold separately) and the word is "recommended". Can it be used with other adapter?

Am I right that if it is used with 20W USB-C then it is a fast-charging
while if used with other lower watt adapter then it could be slow charging?

And can I keep Magsafe charger connected forever. I mean, after I stick it to the wall outlet I keep it connected and ON always because the outlet in my room is at an odd position so it's very inconvenient if I often plug it and unplug it. Will it cause any overheat or damage to the charger?

 

[now i see it]

MagSafe charger can be left plugged into a wall indefinitely.
You can use any charging brick to charge those phones. The bigger the charger, the faster it charges (up to about 20 watts).
Yes a 20 watt charger is a fast charger for those phones but those phones have much bigger batteries than the iPhone 4 did when the original 5 watt charger debuted.