well, first off i'll warn you that fighty inquisitors aren't that hot mainly becaue they're still just basic humans and pay through the nose for their gear!
as for making him better - drop the plasma pistol and grab up holocaust! the carnage this power can cause is never to be underestimated
concerning the retinue, i'd either give that 2nd vet guardsman a meltagun (for 2 total!) or else upgrade him to a second combat servitor... right now though he's simply a waste. same with the sages - go for mystics instead so anything trying to deep strike your inquisitor gets shot first by a nearby firendly unit!
i'd keep the land raider simply because it is some of your only real anti-tank!
IMPORTANT!!! even though it's a dedicated transport, land raiders are still a scoring unit due to their size and insane pts cost!!! (see pg35 codex space marines, last sentance at the top of the page.)
i'd also lose the vet sergeant in the storm trooper squad - if these guys are in combat, something's very wrong
use those pts for more boots instead!
as for the scouts - consider droping the unit down to 6 and giving them sniper rifles? granted pinning isn't as very effective (unless you hide a culexus assassin within 12" of the unit you're targeting!), but the set to-wound roll is gold!
as you have a severe lack of heavy firepower, i'd honestly drop the assault marines and the lance strike and instead go for some devastators and land speeders!
if you're really worried about assaults then pick up a pair of deathcult assassins to support the eversor and daemonhosts
hope this helps,
cheers!