Well for starters, I don't think there's really a need for an M16, seeing as the mod already has an M4, which is essentially the same thing but a bit smaller. Burst fire isn't really something that would fit in HL-style gameplay anyway, as it's mostly used for accuracy, and since HL is run & gun, the accuracy cone doesn't change when you hold down the fire button.
A minigun would be pretty cool, it could work as a drop from the HWGrunt.
Flamethrower would be cool as well, but I don't know where you could get it. If you think you can do a particle flame for it, as well as ignite enemies, go for it, otherwise don't spend the time on it. IMO, it wouldn't be worth the effort if it's just a fireball gluon gun like the one in They Hunger.
As for the self-heal medkit, unless you want to make all the medkits behave like that, and have a carry capacity of about 5 I wouldn't bother. It would only make inconsistencies.