Off the top of my head I think max damage for hammer is 19-35
Sword is 15-22
Dagger is 7-17
Shield is AR16
Bow is 15-28
Not quite sure what you mean by 'regen a hit or more hp' tbh, but vampiric mods allow you to steal health from your opponent with every successful hit.
Max vampiric mods for melee weapons are 3/1 (3 health gain per hit / -1 health degen ~ to clarify, this means you get a constant health degeneration of -1 while you have the weapon equipped but steal 3 health each time you successfully hit an opponent) and 5/1 for bows and hammers (5 health gain per hit / -1 health degen). Personally I think it's best not to have a vampiric hammer because of the slow attack speed and lack of skills which target multiple foes, i dont think you'd be able to get back the health while attacking that the -1 degen would take away. So fast weapons like swords or shotbows are best. (or any bow with barrage)
There are no mods which change the speed of your attacks. Swords swing every 1.33 seconds, axes swing every 1.33 seconds and hammers swing every 1.75 seconds (so sayeth the wiki). Bow refire rates differ depending on the bow and is usually a trade-off with range (
http://gw.gamewikis.org/wiki/Bow)
Apparently you do more damage from haveing a vampiric mod than a sundering (armor penetration, 20% chance being max) one.
Whether you meet the requirement or not doesnt affect how much damage the vamp mod does, it allways does the maximum stated and this is on top of the normal weapon damage. Weapon mods never require you to use any energy, nor do they usually require you to meet the requirement of that particular weapon.
If you do carry a vamp weapon, always carry something else non-vamp in a different weapon slot and switch to it when your standing around doing nothing so you dont die.
Vampiric is always the prefix (ie. vampiric flatbow of...), hp wise the suffix would be fortitude, which is a +hp mod giving an increase to your maximum health (+30hp is the max) while you have the weapon equipped.
Hammer wise I would have thought furious would be a nice mod to have (double adrenaline, 10% chance being max)
From Guildwiki:
"Shields may have a mod which reduces physical damage taken. These always have specific preconditions, such as being enchanted. A shield can have up to -2 (while in a stance), -2 (while enchanted), -3 (while hexed), or -5 (up to 20% chance). There can be a maximum of two damage reduction modifiers (always with different conditions).
Shields may have a +hp mod. The maximum values are +45 (while in a Stance), +45 (while enchanted), +60 (while hexed), or +30 unconditional."
You can't add mods to shields like you can do with weapons so you cant improve them once you find them (or buy them)
Arguably the best shield to have is a AR16 with -5 physical damage (20% chance) and +30hp (unconditional). These are the same stats as the factions endgame exhaulted aegis and also the bronze shields sold by weaponsmiths (or some other npc) in Kaijeng (sp) centre.
EDIT:
For energy, you'll need a zealous mod. Zealous mods are available for all weapons (excapt caster?) and come in only one flavour, 1/1 (1 energy gain per hit / -1 energy degeneration). As with the vampiric mods its X gain per hit on an enemy, so if you've got a zealous bow and you barrage 5 people in one go, you will gain 5 energy.
Links: More information can be found on GuildWiki;
Inherant mods, which cannot be changed:
http://gw.gamewikis.org/wiki/Weapon_modifier
Chageable mods/upgrades:
http://gw.gamewikis.org/wiki/Weapon_upgrade