I read many times the expression くそかわ referred to babies, what does it exactly mean in english?
I know that くそ means "damn" while かわ comes from かわいい, right?
So damn cute?
Yes, right. くそ・クソ・糞 is used in place here for what usually would be すごく, e.g.
くそかわ = すごく可愛い
くそうめぇ = すごくうまい (=すごくおいしい)
(As slang is usually more versatile, there are more expressions with クソ, where すごく isn't a valid substition, e.g. 糞美人. Also, note that くそ isn't traditionally a positive interjection/prefix/..., but traditionally used to embellish derogatory terms.)
I'm not 100% on the precise ordering, but クソ is probably the most recent of a series of similar expressions
めっちゃうまい (from むちゃくちゃ)
まじうまい (from 真面目)
In any case, as you guessed, it is a stronger expression, just as in English:
くそかわ "damn cute"
すごくかわいい "really cute"
As you say, かわ is just a short form of かわいい, as common with all "i-adjectives", うまい => うま(っ), すごい => すご etc.
It means F**king cute.
It is commonly used by gals, but it can be a little rude so I will not recommend you to use it in public.
It is one of the gal language - for more informations on gal language visit http://injapan.gaijinpot.com/featured-photo/2011/09/14/japanese-gal-language-what-is-%E2%80%9Cagepoyo%E2%80%9D/