Later in the game (and after finishing the Wasteland Survival Guide, etc.) is it necessary to wear the Vault Uniforms to be successful in battles (using Small Guns...?) Example: Wearing the Leather Armor as opposed to wearing the Armored Vault 101 Jumpsuit...? :fallout:

The only times in the game when you are supposed to wear something specific it is handed to you by friendlies before you need it. The neural interface suit for Operation Anchorage and the vault 112 suit for the Tranquility Lane quest (not sure if you are actually required to wear this one or not). In all other cases you can use whatever armor/clothing you like.

The vault outfits are never required in order to be effective in combat. The armored 101 suit is useful in the early game because that early it is not easy to find better armor, but the moment you gain access to something better you can feel free to abandon it.

You can complete the whole game in your underwear if you wish. Clothing and armor only provide Damage Resistance (percentage of damage negated directly) and usually small bonuses, and sometimes special effects (like stealth field).