ummm...
It is impossible to even go there without support (from some high power ally), and even if I find one, I might be deadmeat due to lag - sorry, no fun.
there's not just 1 diamond mine. try another one, it's probably safer. if you want to visit dangerous places, you should be either strong or have a good guard. that's in no way different from other games.
ummm...
Same situation in the sewers, which I found first to be something of a training ground - heck - who puts thunder clackers or wrath rats there? they just don't belong! you don't even step out of the load zone and get creamed...
take the other entry? nobody forces you to go in via the one that is dangerous for you.
ummm...
sorry that I need to let off some steam, I see the work involved, but you should listen to all levels of play - and in the thread where you want combat stats, only some powerhouses posted so far... if THOSE get in trouble... well how about the people with lower socres? you don't really want us just trying to smash rogues in Oja, and even by that, we get too few PP to reach a good score, to get anywhere NEAR such scores as mentioned in the aforementioned thread...
there are many different places with all monsters for all kind of strengths. if you have issues regarding the strength of monsters, posting in the according thread just like you did will probably help solving that issue.
just try to keep in mind that devs are trying very hard to give thought to all kinds of playesr, but that's not a trivial task and it's just natural that nothing works 100% alright on the first attempt