Hi, I'm a tau player and next weekend I will be going with a friend to a games workshop tournament. Now I haven't played Warhammer much before, but I have a grasp on the rules.

Unlike most people who start 40K, (so I'm told) I didn't start with Space Marines, I started with Tau, i got a mostly complete Tau Battleforce and a box to keep it in (One of those briefcase sort of things) for £25.
I got in it the following:
Tau Codex,
2 Crisis Battlesuits,
Devilfish,
8 Kroot, (I can't use these because you need at least 10 Kroot in a squad)
11 Fire Warriors,
6 Gun Drones,
1 Shield Drone
and 1 Markerlight Drone.

I also have 3 stealth suits.

Here's My current Army List:

HQ
Commander Tau Shas'O - 89? Points
Stimulant Injector (Gives feel no pain), Rail Gun, Flamer (twin-linked)

Body Guard Suit Shas'vre - 35 Points
(Needs 3 weapon or support systems)
ELITES
Stealth Team Shas'ui 2, Shas'vre - Points 100

TROOPS
Fire Warrior Team 10 Shas'la, Shas'ui 1 - Points 120

Devilfish Troop Carrier - Points 100
smart missile weapon system
FAST ATTACK


Total: 444 Points

Although I have a few questions:
1. What is Strategy Rating? It was removed in Errata, but it still interests me.
2. How do you get the Rail Gun? It is in the Armoury but is mentioned nowhere else and has no point cost anywhere.
3. Are Grenades any good or should I leave them?