If so, which block perks are worth taking if using only a bow?

Nope, none of them work, sadly.

Overdraw (5)
Eagle Eye
Critical Shot (3)
Steady Hand (1)
Power Shot
Hunter's Discipline
Ranger
Quick Shot

Yes, you can bash with a bow.

I can't remember off-hand which perks are viable though, but I'm sure someone'll clear that up very shortly.

I think he meant the shield bash, not the standard bow bash.

If you don't have the bow drawn you can do this sort of punching move to temporarily stagger an opponent.

Well, it that case only Deadly Bash affects it. Not really worth investing in the block tree for that, though.

If you have a bow drawn, but not an arrow knocked you can use the block button to bash (aka punch them with your bow fist). It only consumes stamina and I am not 100% if there is a specific perkt hat does this.

I modified the list above for an alternative to spending perks. Once Power Shot is unlocked, Critical Shot becomes moot. The staggering is the same as a two second paralyze.

As for the question, I've not bashed with a bow, nor have I staggered an opponent with blocking. If it's possible to bash, I would have to assume forward movement would be required. In a non-moving block, damage is simply reduced, but not by much. I don't recommend blocking with a bow at mid to high levels.

Yes, you can bash. Moving or not, it's a great way to fight in close quarters as it allows you to take another shot or block a sword swing. (you really feel tough using it)