I remember in FO3 in the early game I'd try to repair things but once an item got to say 50% durability I couldn't repair further and it would tell me a repair skill of XX was required.

In NV I seem to be able to fully repair everything I've run into with Repair in the 30-50 range. It seems like maybe repair is only use at the workbench/ammo bench or for specific dialog/things.

I'm curious about this too. I was able to repair things to 100% from the get go. What gives? That essentially means repair is only good for crafting and related perks. Is this actually the case? I wouldn't even have bothered putting what I already have in repair if I knew that beforehand.

Repair does not effect maximum condition. It effects how much is repaired per attempt and ammo crafting. High repair makes repairs quicker and cheaper.

Does it effect the amount repaired per Weapon Repair Kit as well?

Ah, okay.

Don't know, haven't dared use one yet. I should check!

I've used them, and they work...but poorly. Certainly not worth the effort of collecting the stuff/making one. Though the character I did that on had pretty measly repair skill.

So, to understand, if I repair a shotgun, using other shotguns to 100%, it really doesn't affect it's damage ability? I have to use the weapon repair kit to get it to maximum damage, even if it shows at 100%.

100% repaired.

Max damage is achieved at ~ 75%. It does not matter how you get to that point. It's the point with the little mark on the condition gauge. Above 75% it's just "maintenance" a buffer so you keep that max damage.

Edit: No, no no. Lets say you have 30 Repair and you have three broken Shotguns. And you combine them you get a Shotgun with 45% Cnd. But if you have 100 Repair you might get a Shotgun at 75-80% Cnd. Damage and/or armour increase included in both.