1) Bear in mind a lot of classes and cabals are somewhat time relevant, as well as other things in the game. By slowing down time, depending on how drastically you would suggest it gets slowed down, can potentially shaft these classes/cabals or enemies of these classes/cabals. Here's an example, I'm a low 30's elf warrior with a rank 40 evil conjurer in my range. Normally I have to wait from 7PM to 5AM to avoid being nightgaunted. That's like 15-20 minutes, give or take, since ticks aren't a minute exactly. If instead, it was say, twice as slow, I'd have to wait 30-40 minutes. If it was 4x as long, now I'd have to wait an hour or more, just to avoid being nightgaunted.

Also, all affects are time based. Sanctuary for 6 minutes is one thing, sanctuary for 20 is another.

2) I believe weather and time of day do have an effect, but I'm not positive. I know scan can be affected by things, just not sure what the exact details are.

3) This would be cool.

4) Some towns pay more for goods than others, I don't think they'd make it distance based since, honestly, it'd be a lot of math overhead at very little significant payout. Not sure what you mean by items fading.