[Sokhar]

To put it politely, these ideas are really rather unnecessary. To be frank, most of them bite. I'm all for expanding on the Guard's options (and if you search way back when, I ran a series of "Codex Revisions" threads that were about modifying existing units to be more useful or adding new ones in), but most of these wouldn't elicit more than a chuckle and a crumpled-up submission from GW.

"Veteran Guard Commander"--White Dwarf published the rules for the Imperial Guard High Command Group. That's your higher leadership officer, the rules for different orderlies were nice and balanced, and I believe I recall Grenadier attendants as an option. The reason Command Squads don't get BS 4 might have something to do with them having access to 4 special weapons. Give them Marine ballistic skill and everyone starts having a suicide Command Squad equipped with plasma guns that can melt a Space Marine Squad in one round of shooting. Don't think so.

"Commando Squad"--For pete's sake folks, we have Storm Troopers and Hardened Vets that do this same exact thing. Sniper rifles are effective in real life but not in 40K. That's for a reason, now get over it already. Storm Troopers are elite and survive better than regular Guardsmen because they're not idiots throwing a huge IED at the enemy. When they blow something up they do it with melta bombs or krak grenades, not something that can blow them up just as well as the enemy. If you want more demo charges, go play Elysians. Pass.

"Guardsmen Bikers"--So except for the option to get a heavy stubber, how are these guys not Rough Riders? If you want the extra toughness of a bike, go for the Xeno mounts doctrine. Call it something else on your army list, but there you go. A normal human on a motorbike still ain't hard to kill. I'm all for a genuinely fast option for the Guard, but I lean towards jeeps, hummvees, halftracks, or something similar. If I can manage to find it, I'll post my write-up for such a vehicle, but Guard bikes are going to be the realm of conversions not actual unit choices.

"Tank Hunter"--We already have the Leman Russ Vanquisher and the Destroyer Tank Hunter. Is there a point to this thing?

"Linebreaker Squad"--Uhm, read the Codex lately? Last time I checked there's a unit called "Hardened Veterans" that does this exact thing. Waste of space.

"Hitman"--Flak, either act out your urges on the videogame of the same name or just buy a Vindicare Assassin. In the 40K universe one human with a sniper rifle doesn't mean jack.

As for other suggestions....

Penal Legion--Conscripts with creative modeling
Human Bombs--Doubt we'll see those in the era of political correctness
Thud Guns & Rapier Laser Destroyers--Imperial Armour has some options for artillery pieces, but I think this idea has the most potential out of anything mentioned here. Low-grade "field artillery" below the level of a Basilisk or Manticore is a decent idea I've had before. The problem lies in making the guns such that they are useful but don't step on other heavy weapons' toes. You figure out how to do that successfully, let me know.