To be honest it sounds quite a lot like my 1st serious relationship, I did a lot of stupid things then similar to what your bf is doing, how old are you/him? is it his 1st serious relationship? (it doesnt help you but if this is the case its probably why he does these things)
sometimes you lie because you think it will be better, you're scared of how the other person will react, and feel its best they dont know (but usually they do find out) but you cant exactly say to your girlfriend: "I have porn" or whatever, its just not done...
If he does care about you a lot he'll realise that he cant carry on lying to you (have you explained to him that you hate him lying?) and will try to change, it may take time though, these things become a habit...
If you think its worth it then tell him he has to try and change what he does, if its not, or you think that there are things that wont get any better, then its best to just leave the relationship...