Greenstuff flames are a tough one. Especially on a sphere, but here it goes (btw- this kind of question could've gone in the modeling section)
1- create your GS ball, and stick it to his hand with glue. LET IT DRY! this will be the core of your great ball of fire
2- start turning up the heat by adding a cone of GS in the direction of the flames.
[a note on blending: if you're not experienced with GS or sculpture, it's important that you know how to blend. With a wet finger or the wet handle of a paintbrush, press and drag the ends of GS down towards solid point that you want to blend them into. Light pressure and a gradual slope will make it look like a single solid piece. This is great for adding length to robes and capes as well]
3- with your cone in place, get out your modeling clippers and start harassing the edges of your cone. You want to make vertical cuts, parallel to the center of your cone, and pull the cut bits out away from the base of the flame. This should make little tongues flame.
3.5- the cut out triangles get mounted to the outside edges of your cone, to bulk it out and help to cover the sphere.
[remember that we're working with heroic-scale models, to get good looking flames, you want think ropes of flame, otherwise your flames will look too detailed for the rest of the model, and will be too fragile for transport]
4- blend the flames with your finger or brush so that they recede back into the sphere. Ideally, you'll have the back 1/4 of the sphere showing (not counting the part that's flat against his palm). If you want, you can use a wet knife to carve some little lines into the base sphere to make it look like there are flames there. I'd just leave it alone personally.
5- painting. Remember that fire is reverse shaded. The darkest parts of the fire are on the OUTSIDE. I paint my flames with a white base coat, then paint the lightest shade (flame heat is clear, blue, white, yellow, orange, red from bottom to top, pick about 3, avoid blue) From there, I use inks or thinned paint to add the subsequent layers. Paint these inks on by holding the fire upside-down, so that you can start at the recesses and let the ink run OUT from there. This will give a nice gradiated look. If you want, you can add a glaze of gloss varnish tinted slightly yellow, this will help "pop" all the colors, and also help blend them together.
[Working with different colored flames, like green or purple, just stick to the same principle. Remember that white is a neutral color, so starting all flames with white is always good. Just wash with a light color that is somewhere along your color spectrum, instead of the yellow tint that I suggested]
--------------------------------
As for your original question on wargear layouts:
I second the idea of ReaverBow, Mask, Heavy Armor, Great Weapon, BSB
I've put that noble into a regiment of LSG in a small game. 20 LSG + BSB noble makes for 3 rows of 7. That's 7/14 shooters during a stand and shoot, and a full regiment fighting in melee. With a BSB and possibly a Warbanner on the regiment's standard, you'll do just fine. The massed volley of shots is quite the deterrent for enemy chargers. In low point games (+1250pts), I've used this regiment as an anvil. Mixed with an RBT, and a mage, you can usually pull the enemy towards you and force them into a charge.
Don't put a shooting model into a regiment of spearmen. It just isn't worth it. Spears are cheap, they don't benefit from an S&S reaction, and they need to be mobile. As the cheapest regiment in the army, they should be usable as an acceptable 'sacrifice' on the field.
