My Cleric was turned into a Vampire..

[JeminiZero]

1) Will his alignment change too evil?

This depends partly on how undead are treated in the setting (ask the DM), which is tied to what is the exact nature of the negative energy plane (NEP) which powers undead. If the NEP is just another plane filled with energy that just happens to be harmful to most normal life (not unlike the elemental plane of fire), then undead are not necessarily evil, and your cleric will likely retain his alignment.

If on the other hand the NEP itself is evil, then all undead which draw from its power will be influenced by it, meaning your cleric should become evil... although the process may be a drawn out process of slow corruption rather than a sudden about face.

2) Will he loose the ability to cast Cure spells spontaniously?

If his alignment doesn't change, and the character's diety doesn't disown the cleric outright, then no. The ability to spontaneously cast Cure spells is a gift from the diety rather than selected based on what cure/harms you. E.g. evil clerics cast inflict spells which are harmful to them if they are living, but heals them if they are undead.

If his alignment changes and he somehow starts drawing power from an evil deity, then I would say yes, he stops spontaneously casting cure, and starts casting inflict.

Edit: In the case of Eberron, replace "Ideals" with "Deity" and you get essentially the same thing. Your character will likely continue to spontaneous cure if he remains good, or spontaneous inflict when he becomes evil.

3) If he remains Good aligned wouldn't he just try and kill himself?

The big problem with vampires is that they need blood to survive. Most get by preying on other sentient species, but this isn't strictly necessary by RAW. In other words, your cleric could hunt animals for their blood and live (or unlive as the case may be) with a clean conscience.

Also, there might be a cure for vampirism making suicide unnecessary.