First of all I'll repeat a bit of advice that was told to me when my son was 14yrs old, and I think was instrumental in us all keeping our sanity! "14yr old boys are the sh*t of the earth, but they do come out of it". Yep. Describes them well hey? This was told to me with all due respect from the school psych and year co-ordinator. They also told me to remember when they were toddlers and there were some tantrums/behaviour that you just had to 'step over'. They said that 14yr old boys are like toddlers and sometimes, even though they might be being rude or argumentative, you just have to 'step over them'.
That helped me for the general awful behaviour, but of course it doesn't help with the specific stuff like wagging and lying etc.
We have another boy who is 14yrs old now and doing similar to yours. Every time we catch him, he says, "I know now, I won't do it again". But next time it's something else. We're questioning him on his values at the moment and where his line is. Where is the line that he won't cross, because he doesn't seem to know.
At the moment he's in the middle of a grounding and electronic device blackout.
I agree with getting some older, but not dad-old, good influences around him if you can. Youth groups can be handy for that if he's open to it.
We're making our current 14yr old do some work with a psych as well as some homework on boundaries etc, in order to work his way to getting his phone etc back.
Oh, and I'd also highly recommend always having your kids' passwords. It's generally YOUR equipment, not theirs anyway. (ie: you paid/pay for it) Just tell them, don't give me any reason to look and I won't.