Does the phrase 'little too' mean same as 'very', or is it mild form of very ? For instance, I am little too comfortable talking to you. Does it mean same as 'I am very comfortable talking to you' ?
First of all, it should probably be "I am a little too comfortable talking to you".
And being "a little too X" doesn't exactly mean you're "very X" - just to a degree that you consider slightly above the limit. So being "a little too comfortable" talking to someone means that you're just slightly more comfortable talking than you feel is appropriate.
Also note that depending on the delivery, it might either be a genuine concern, or a joking acknowledgement of the relationship growing.
It depends on the context and the tone of the speaker/writer.
Literally, the two phrases have very different meanings. If something is "a little too ___," it means that something is just barely above an acceptable limit. For example, "the bath water is a little too hot, so I'll wait before I get in." If something is "very ___," then it means "to a high degree or extent." For example, if you say "the water is very hot," that implies that it is hotter than if you just said "the water is hot."
However, sometimes "a little too ___" can be used humorously or sarcastically to mean the opposite, implying that something is far beyond what's acceptable, especially if the speaker emphasizes "little." For example, "the gunshots were a LITTLE too close to my house" would probably mean someone fired a gun near your house and the bullets were close enough to make you very, very scared. In this case, the speaker is using understatement to emphasize just how terrified they were.