I did specify that the Ranger should be taken first.
Rangers are limited to light and medium armors, so mth chain would be the choice to minimize arcane spell failure. And I think you mean Still Spell, not Silent Spell, as the feat. All he has to do is not roll a 1 or 2 on a D20 and his spell goes off.
For most battles I've seen 10 rounds is quite enough for a buff spell like Enlarge Person. Buy a wand of it and you can do it as needed, and no spell failure %.
Note that Enlarge Person also enlarges your weapon, so a 10 foot reach with the chain becomes 20 when Enlarged, and Combat Reflexes w/Improved Trip can get pretty nasty. You control a 50 foot circle of that battlefield (20 ft on each side, plus your 10 in the middle), and nothing moves on it without your permission.
As for the ability score splits: He's doing a 40 point build, which is more than a little over the top.
Spend 13 on Strength, for a 17, and add your level bonuses to it to get 20. <edit>Correction, he has +2 from levels until level 12. My mistake</edit>
Spend 6 on Wisdom, for a 14. Good enough for your Ranger spellcasting career.
Spend 6 on Int, for a 14, giving a Human Ranger 8 skill points a level. Plenty for everything.
That leaves 15 points to split between Dex and Con, with Cha as your dump stat.
In this build the familiar and animal companion help in scouting duties more than combat. Scouting is one of those things a Ranger type is supposed to be good at.
For armor items, less is more. Multiple low bonus items are far cheaper than a single large bonus item. So Ring +2, Natural Armor Amulet +2 at 4k each are a bargain. Adding another +2 to a Mth Chain shirt puts AC at 20 + Dex, and 24 + Dex when Shield is up. Respectable for the level. That's 13k of your money, leaving 23k for weapons, wands, and misc.
I've run variations on build successfully. He isn't overwhelming at any one thing (though he's hell on wheels in an open field combat). But he's versatile, and that helps him survive, which was a good part of the challenge presented.