An 'Epic Levels' (or close to them) rant

[S'mon]

Likewise, a trade negotiation worth 50,000 gp sounds like it would worth as much as whatever average encounter level is worth around 50,000 gp (SRD says its about an EL 18). Afterall, a negotiation where 10s of thousands of gold are being thrown about sounds like quite an experience. You might only reward 50% xp since a trade negotiation isn't usually life threatening. But it should still be worth a lot of xp at that level of gold.
Yes, but that is an average over the life of the world, not a fixed limit. Maybe the world is having an age of heroes when there will be 10-20 epic characters running around at once and in a few centuries they'll die off and the number will fall to 0 for a millenia until another age of heroes arises. That's my perception. YMMV.

I just killed off all the aforementioned Epic NPCs in Thrinia BTW.

Re negotiation for money, to me it depends on the difficulty of the challenge, not the amount. Eg IMC the 18th level Warlord PC recently extorted 800,000gp from the kingdom he was threatening, half of which went to his horde, but I'd say it was only a moderate challenge, the kingdom felt they'd got off quite lightly.

 

[S'mon]

And for that 90 year old woman... by giving a person all those levels to get all those skill ranks you've technically got a 90 year old woman who could singlehandedly clean the floor of a tavern filled with bloodthirsty and drunken 1st level warrior goblins. The game mechanics involved in giving her skill points to be all wise and knowledgeable also make her into a killing machine in the eyes of those poor goblins..

With -6 STR DEX CON, a 5th level or even 10th level Commoner woman will be little threat to goblin War-1s, her physical stats will probably be in the 1-4 range...