please excuse my noobynes when it comes to bows, but I have a few questions.
1 the damages is the bow damage + arrow damage, right?
2 If I have a silver bow, but not a silver arrow, do I still do damage aginst ghosts?
3 If my enchnted bow is out of charge do I still do amage aginst ghosts?

Your bow damage + your arrow damage + any poison damage + whether you are sneaking or not
Yes on number 2
Not sure on number 3, I always keep my bow charged up to some point, but I would assume it to be yes, as it is still an enchanted bow.

Yes, a discharged weapon still damages a ghost. It's still "enchanted" even though the enchantment isn't working.

Interestingly, according to the wiki, if you put poison on a normal weapon, it will work against a "resist-normal-weapon enemy" even if that enemy is also immune to poison. The poison won't work, but the weapon will do its normal damage.

Ghosts are 100% immune to Poison, Frost and Normal Weapons.

The poison "enabler" thing isn't completely explained. I wonder what happens if you use a poisoned frost-enchanted weapon against a ghost? Does the poison allow the frost enchantment to work? Or do you just get the base damage? The frost enchantment obviously makes the weapon not normal, so it bypasses the "Resist Normal Weapons", making the use of the poison redundant unless it gets the frost damage through.

I have a feeling that the poison effect wasn't intended. I was surprised when I read it in the wiki. It wouldn't have occurred to me to try poisoning a ghost.

thanks guys

It would appear that poisons are technically a sort of temporary enchantment. So no, the poison wouldn't allow the frost enchantment to work, it just bypasses the resistance to normal weapons.