Minimum Feats for effective Crossbow use

[Side]

As part of my never ending quest to fit too many things into my favorite character builds I've taken a look at the Crossbow Sniper feats. Having a ranged weapon as a backup damage source for a melee character has been very useful for me over the past few years and so I'm looking into making it a legitimate, albeit secondary threat.

That said I highly doubt only using the two Crossbow Sniper feats will be enough. There's also weapon focus to boost the Crossbow Sniper damage, Rapid Reload, and others that turn the crossbow from being just another weapon into something of note.

So my question is this; if you were to make the most condensed crossbow build possible what feats would be absolutely required for viable party use, and which can be passed up? What feats are available on items in game (I know point blank shot is one of them), and what ones will have to be chosen/ignored?

[Stonebar]

Other then sniper, the Rapid reload and rapid fire feats are a must. Crossbows get a max of 1 single attack per round regardless of level. Those two feats add 1 more attack each, for a max of 3 attacks per round. Crossbow is a bit feat heavy which is why they are not common especially in epics, when dwarfed by the 7 attacks of a bow, and the bows initial 3 attack flurry vs. 1 for a C-bow. They can be fun though, but if it's a secondary weapon it's likely not worth the minimal four feats.
There's also if you have the 4 fighter for the Weapon Specialization feat; Ranged mastery. Mutishot is good for all ranged, but the heavy negative to attack means lots of ab feats are needed to compensate as well.

[Side]

I was afraid of that. I like crossbows for the RP aspect, but bows seem like they would be easier to use as a backup damage source, in case you are low and out of healing but still want to help with the fight.

[Kiran]

Crossbow fighters are gods till you hit 21, then you might as well be a bow person.

However with haste you get 2 shots, so could make a weird fighter/warlock combo for the constant haste.

I was doing non crits at around 80 at level 12 on Xvarts. Peaked at 20 for around 90-95. I was a dwarf.

If I was hasted by a warlock I shot twice for the above damage, 1 hitting xvarts. Multishot is your friend. Rapid fire too. Pump that dex. Try and aim for 3-4 might atleast. Try and get extra bludgeoning damage. Unlimited +2 or more bolts great too. Had a arbalist that was +2 and +4 might with +2 bolts. Very handy.

[Side]

Well, I'll have a dex modifier of 10 by the time I hit level 30. Thing is I have two open feat slots without some serious rearranging, and I'm 3k exp from level 21.

It's rare that I have to switch from melee to range (usually because my AC isn't high enough for certain things) but when I do I'd like it to feel like I'm still being useful. I don't have to be a primary damage dealer in my group, I just don't want to feel like dead weight.

My secret wish was that there was some way of getting weapon focus crossbow with an item (probably on a crossbow) that would make taking the two crossbow sniper feats worth while. I'm using a fantastic light crossbow right now (+3 AB, +4 Mighty, unlimited +3 bolts), but even so my damage with it is rather pathetic.

Looks like I have my answer though. To be an effective crossbow user you have to invest and not go for an absolute minimum build. Oh well, thanks for the help.