[Xandax]

Take Perception to 8 minimum.
Agility at 10ish is always good due to getting 2 aimed shots off.
Str. doesn't have to be higher then 5.
Luck at 6 is always my recomandation.
Endurance at around 5-6, you don't need terrible many hitpoints cause you should stay out of the imidate line of fire.
Charisma what ever is left - I often only ran around with 4/5 charisma.

Tags:
Go for Small Guns definately. The others are importent for a sniper (yet).

Traits: Take gifted and Finesse (or shift Finess for something else, cause of its lower importance in the late part of the game).

Perks:
Awareness
Better Criticals
Bonus Rate of Fire
Sharpshooter
Sniper
Tag( get energy weapon skill.)

Unlike many I don't think you should go with the "More Critical" Perk because the Sniper perk will effectively negate it.
Sniper makes your critical chance equal your luck - so if you have 6 luck, you have 60% chance of a critical - wich is one reason I recomend good a luck stat.

When you level up, level to about 150% in small guns - don't go much over that score, at level 12 when you get access to Tag, select Energy weapons and level that skill to minimum 150% also.

The weapons to use is imo, based on playing and statictics, listed from beginning of game to end game (thus I recommend the Sniper Rifle over the Hunting Rifle).
Small Guns - Rifles:
Hunting Rifle (scoped)
Assult Rifle
Sniper Rifle

Small Guns - Pistols:
Magum .44
.223 Autoloader

Energy Weapons - Plasma:
Plasma Rifle
Turbo Plasma Rifle
Pulse Pistol
Pulse Rifle.

The Pulse Rifle is the most damaging single shot weapon in this game with this character set up.
Only weakness is that damage is electric and Tesla Armour is good versus this, but I've yet to find many people wearing Telsa Armour. Towards Power Armours the Pulse Rifle is better then the Gauss (wich is why I don't recommend the Gauss much).

Equip your party with what ever weapon you like them to use, they will not do much if you get a decent sniper up and running, then they are mostly there to divert fire from you while you can pick off enemies with 1-2 shot.
Except for end boss(Horigan), I think I've killed one of all types of enemies in the end game with 1 shot from the Pulse Rifle.