Pistol and forward grips make a rifle easier to control which makes the weapon safer. One of the key gun safety rules is to never point the gun at anything you don't intend to destroy. Better control will enhance your ability to avoid negligently shooting yourself or another person.
Concealability is a concern specifically because many states have different requirements for handguns versus long guns. I have no issue with establishing a minimum overall length for a rifle. The ATF has already established special rules for short barreled rifles (SBR). The minimum is around 18 inches. SBR permit investigations IIRC take 6-9 months rather than the current 3 day max for a standard rifle. Please see #5 for more info: https://www.democraticunderground.com/1172212301#post5 However, being concealable does make the gun more deadly. I wouldn't recommend an AR for home defense but, because of the versatility of that platform, I recognize that some do. An adaptable stock may be very useful in that scenario.
Also see #5 regarding the grenade launcher. Previous AWBs have included as a qualifier 'the ability to accept the attachment of a grenade launcher' or some such language. Actual grenade launchers do require ATF investigation and approval beyond that of the regular background check as do any grenades. I certainly agree that grenades are deadlier than rifle rounds.
Preventing someone from accidentally burning a hand doesn't make the rifle more or less deadly. The chance of burning your hand makes it less safe.
A suppressor (silencer) would reduce the sound of a gunshot to about the volume of a chainsaw a few feet away, far from an undetectable level. Suppressors are still ATF restricted and not generally available.
The overall point of HR 1808 is ban guns that look like this: https://en.wikipedia.org/wiki/Bushmaster_XM-15
The thing to be aware of is that this law doesn't affect this gun: https://en.wikipedia.org/wiki/Ruger_Mini-14
Keep in mind is that both of these accept the same ammo, fire at the same rate and will produce identical wounds.