Those brakes don't exist, do you mean M365? They ain't too bad, fairly similar to a lot of other Shimanos without servo-wave, but they could be better.
Rotors won't make much difference at the same size, Ice Techs won't heat up as much on long braking periods but that's it and honestly you probably won't benefit from it. Larger discs will also heat up less as well as giving you greater leverage.
Organic resin pads actually have more initial bite than sintered metallic pads and are also quieter, metallic pads have the advantage of fading less at high temperatures, perform better when wet, and they last longer. You can also get other compounds that behave similar to organic but have kevlar reinforcement for heat resistance and longer life.
I would suggest that to get the results you're after you should get M675 brakes (best value for money from Shimano) and try them with the stock pads, if they wear down too quick look at kevlar pads unless you ride in the wet a lot or you're a big guy (bigger riders produce more heat from braking). Similarly you can look at larger rotors to reduce heat (floating rotors even more so).
It's also important to make sure you bed the brakes in properly which you can even try with your current ones to see if there's any improvement. Lightly sand the rotor and pads and clean them well with soapy water, get up to a decent speed and apply the brakes hard but don't come to a complete stop, repeat about 5 times or so.>>1089079
As the previous replies have said, take it to a shop. It seems like something is definitely wrong but with your limited knowledge there's not much we can do to help.>>1089084
They're good from the first use. Disc brakes coat the rotor with material from the pad and mate the surfaces, that's not the case with rubber pads on rims (if the pads are aligned properly, if they're wonky the braking will improve as they wear to contact the rim completely flat).