Welcome to the party Baldar89, there may not be cookies but we got squig pies and fungus brew!
Your list is certainly interesting, and totally capable of being bumped up a notch to take on those Nids, so let's get to it...
Waz is really the only Special Character HQ I like, nevertheless I don't think he's a good choice without a serious overhaul to the list. His main power is allowing you to bring standard Warbike mobs as Troops, which your list is lacking, and while his Dakkacannon is great for instakilling the little bugs and knocking wounds off Monstrous Creatures, the better bet is a BikerBoss which is typically 30 points cheaper even when you kit him out. A standard Biker Boss also has other advantages over Waz such as higher Str, option to have an additional attack than Waz, can get the Cybork Invul save, and has the option of taking a Big Choppa which would allow you to attack with his higher than average Initiative (which with the exception of Genestealers, Lictors and Nid Special Creatures is higher than Nid Ini).
Skeetergod mentioned the Big Mek a little bit, but I personally differ on him with the idea of a SAG attached to a Loota Squad. Yes Lootas would benefit from a Bosspole, but the negatives are that the SAG would have to target the same unit, and on the dreaded double 1 it's almost guaranteed to take out a large chunk if not the entire Loota unit. When I play with the SAG I like to have him accompany a unit of 19 Grots (at 19 you only need 1 Herda).
Grots are cheap ablative wounds for the Mek, especially when you have the unit in terrain that gives both wide Line of Sight to the battlefield and a decent Cover Save, not to mention in late game they can run off to guard homefield objectives or even detatch from the Big Mek to assault an enemy MC that's gotten too close. Grots verses MCs are surprisingly great, not because they can kill one, but they can tie one up for multiple turns, sacrifice 1-3 to stay in the fight, and multiple Herdas really enhance this ability by knocking off attacks with a Grabba Stick.
Also look closely at the wording on page 97 on the Big Mek's options, he can't take both a SAG and a KMB, it's one or the other, and against Nids I would strongly advice the SAG, which has a statistical average of 7 (even though it usually doesn't feel like it).
The Nob Bikers... well take Skeetergod's advice and drop the Shootas and Ammo Runts, maybe even drop one of the banners. I can see where your were going, it's good to have a backup in case the Banner carrier gets Precision Shot to death, but it's cost at being 2.5 Boyz is a bit too steep to bother taking two, at least in my opinion. Like Skeetergod said (but I feel it needs repeating) this squad really needs some Pks, I'd say 3 max, but that's just me.
One thing to consider is just how point heavy a full squad of Nob Bikers is, almost a third of your army list. That's a huge percentage that will be really difficult for them to earn back. Certainly not impossible, but there's a reason why I'm not a fan of "Deathstar" units. I can easily see someone who isn't very experienced (no offense is intended by the way, we were all newbies at some point!) bringing a 10man of Nob Bikers for the exact reason that they would start out in the 550 point range before the trimings of extra weapons, and that squad lets me play larger games without too many extra models. (Heck when I started out I was planing the same basic thing with not one but 2 10man squads of Wraithguard, what held me back was the pricetag)
Some people swear by the Deathstar unit style of play, I'm not one of them, and personally I think it's the antithesis of the Ork gameplay style of multiple redundancy. In simplest terms what I'm saying is a backup to the backup plan (and maybe a third Plan B on top for gravy). You want to be flexible, and be able to handle setbacks such as a unit or two dying without it seriously hampering the strategy. And with Orks the general strategy is shoot, stomp, move on. Of course that's just my take on it.
Two 20 mobz of Boyz seems really light. Like a spoonful of beer in a large glass of water and being called a 'light beer' light. It's not that 20 mobz don't work, it's just I've never seen them work when they're not in Wagons or backed up by 2-4 more units of 20. Of course that's been my experience, and experience is the best teacher. Anyway the Eavy Armor is generally a waste, there's a lot that can still bypass the armor and it is generally cost prohibitive. I think it's great on Nobz leading a squad but even then it's debatable. Similarly to Skeetergod I hope these Boyz are of the Shoota variety, which I believe have finally risen up to end the Shoota v. Slugga debate.
You mention in the end of your post that you're going to write another list with Heavy Guns and huge mobz, and at this I really must make a suggestion. Instead of it being a completely different list, smash that in with this list. Artillery rules are Boffo, and the Kannon itself is the single greatest Anti-Nid weapon in the Ork arsenal (can reliably take out blobs of the little critters, knock off wounds from MCs, and can access cheap rerolls for when you need it). The list itself can open itself up a bit for additional units, and overall that would compliment it greatly.
Peace
~OD