On the topic of hideous blow: I would recommend you swap out for Eldritch Glaive from dragon magic (p. 82) if your DM will allow it. Once you hit 4th level spells and you can bump your BAB up to your HD total, multiple attacks will increase your round by round damage significantly (it also makes touch attacks and provides reach, though you would lose the "from weapon" damage and not be able to use enhancements on it). Both have their place, but eldritch glaive allows you to spend your GP on more defensive gear (which you will probably need with limited AC/HP).
On the topic of race: This depends largely on what you plan on taking as your invocations.
If you plan on taking lots of the essence invocations that have a saving throw component, you need a race with a good charisma rating. I think a Spellscale from races of the dragon are a good bet (charisma bonus, and you get a daily meditation that can be very useful -- I think RAW the Bahamut and Tiamat meditations should work for your eldritch blast).
If you plan on focusing more on utility powers, charisma is less important and other ability scores have more to offer. Given this, I would recommend a strongheart halfling (your strength bonus isn't going to provide a big bonus to attack/damage with a character focused on casting/invocations). You get an effective +2 to AC and if you spend the racial bonus feat on weapon finesse, it also boosts your attack. This allows you to focus on fewer ability scores, which is always a bonus.
On the topic of feats: Going eldritch disciple costs you one of the better defensive abilities that warlock offers: damage reduction. By taking the Fey Heritage feat chain from complete mage will net you some cool abilities including up to DR 5/cold iron, while giving other bonuses like +1 to DC of enchantment spells and invocations and a host of SLA's like charm monster, dimension door, and summon nature's ally V.
Hope this helps,
Amaranth
