I want to ask about RB260GSP, from the website, it say it have POE output at port 2-5 same as the POE input..
It is mean if i use POE 24V connect to ether 1 to give the switches power, i can use the same POE output 24V for ether 2-5?
Will it be too hot or burned?
Do i need to have another DC power?

Yes indeed, i use meanwell power supply's 27 volt 1.8 amp.
Model AD-55B

RB260GSP is limited by how much current it can pass along, and that is limited to 2A in total. So , if you are using 1.8A PSU, you are limiting yourself, as a switch by itself is using some power. This is why They are supplied by 2.5A @24V power supplies. SO, if you are getting different voltage PSU, make sure you have it rated over 2A so that hardware can perform to its fullest.