Since I can't find one mod that does everything I want, I'm using two or three. Right now, I'm using http://www.newvegasnexus.com/downloads/file.php?id=34890 because it's the only mod that gives all the loot a serious cut. On top of that, I have my own mod, which does a combination of making SPECIAL more relevant (and more like classic FO), making SACs less godly, and making combat a little more challenging all around. Adventurers is supposed to also weight all items, but I'm just starting and already finding things that don't have any weight to them. At this point, I'm thinking of doing two things:

1) Getting another mod that does put weight on everything (I'm thinking Realistic Weights).

2) Expanding on my mod to tweak weapons a little. Specifically, I want to remove the zooming without a scope.

What I'm wondering is how that would work out. That is, if I have three mods, and their effects cross over, how does the system determine which ones take precedence? Will/can Realistic Weights override the weighting of items while keeping Adventurers loot reduction? Or, can the items weighted in Realistic Weights also take into consideration my disabling zooming without a scope (which I believe has to be done with an item edit and not setting tweak)? Thanks.

Which ever one is lower in your load order should take precedence, but only for the overlapping features. For example, one overhaul mod won't overwrite an entire other overhaul mod just because one little feature they both share is conflicting.

The mod that is lower in the load order wins.
For example you have two mods that edit the same weapon, then ALL the values of that weapon that are in the last loaded mod.

Or if you had 3 mods called a.esp, b.esp, c.esp that edit all the same items and they're loaded in this order.

Fallout.esm
a.esp
c.esp
b.esp

then the game will only use the values that are in b.esp for those items that conflict.

So, how do I change the load order? I don't see an option for it in the Data Files menu.

Download thehttp://www.newvegasnexus.com/downloads/file.php?id=36901 (short: FOMM) from Nexus.

Also, utilities like Wrye Bash or FNVEdit can merge some items that otherwise conflict. Heck, technically everything could be merged to get all modifications to them if you do them manually in FNVEdit. You have to know what you're doing, though.

Yes, if you want for example a new armor model from one mod and values/properties for it from another you're going to need to merge the mods' changes with a patch. BOSS, Wrye Flash and FNVEdit are the tools i use for it, not easy but very powerful.