First, I'd like to start off by saying I think these are all great ideas.
So for my recommendations:
I think the speed buff suits the Halfling race well, as their tiny size would make it easy for them to get around.
Maybe for a Halfling, a shovel can do the amount of damage that a vanilla axe does, possibly less. This would allow us to take care of mobs, but it wouldn't give us an advantage in a PvP situation.
I, personally like the slower hunger loss best. It makes sense that Orcs being so large would have to eat more, so Halflings should need to eat less.
You point out that Halflings fitting in one block tall spaces would be too OP. However, is it not entirely realistic? Halflings are typically three feet (One block) tall. While I don't think that it would necessarily be a good thing, it'd be a completely realistic mechanic in my opinion.
And lastly, I have to admit that the High Elves having magic resistance and increased mana is a little much. There either needs to be a de-buff added (Which I find the better solution), or one of the two buffs removed. Even being a High Elven mage, it seems a bit OP.