Yes, as the title indicates, I have three modding questions, that inexperienced people like myself would not be able to answer, but people experienced with the files and modifications of GTA would know. I'll list them out below:

1) A few months ago, while looking for ways to increase NPC crime, I came upon a thread there that said its possible to increase gang violence by setting a variable in the pedgrp.dat, peds.ide, or some file of that sort from 0 to 1 to make them aggressive, or "hate", towards other gangs and the player, increasing the likelihood of hostile actions. Unfortunately, my forgetful self failed to save the page, and despite deep searching on the site at GTAForums and Google, I can't find anything similar. If you know of this solution, would it be possible to repost the solution?

2) I am using a modified timecycle in my game that increases the brightness of roads, and parts of Liberty City, particularly Union Drive East/West, are not covered by some HD road textures I downloaded. Are there any road textures that cover all roads in Liberty City?

3) Also, I currently use the TrafficFlow V5 fix for the taxi bug, but I would like more vehicle variety besides the 24 vehicles that already spawn. I know this has already been discussed, but is it safe to install multiple TrafficFlow scripts, each spawning vehicles less often than separately, and each having combined the same chance of random dispatch compared to just using one script? I would really like more vehicles, and I've found TrafficFlow is my most stable solution for the taxi fix.

Any answers are greatly appreciated.

I can answer number 3 for you

I have trafficflow and a duplicate called trafficflowtwo installed, both with different car lists. I've grouped a number of ordinary cars into trafficflow and given it a higher spawn chance than trafficflow2 that has rarer cars like sportscars and trucks.

What do you seem to be getting in terms of stability and crashing? I'm crashing every 15 minutes right now with two TrafficFlows, with one loading every 20 seconds, and another loading every 40 seconds.