JL'sMom... oh the picture and handprint thing... my DH totally would have had the same issue with that (and has with pics) nine months ago...
Counseling has brought so much to light and has really helped.
DH was dealing with a lot of guilt of not being a part of his DD's life everyday and wasn't accepting the whole aspect of blended, and the whole idea of fair doesn't always mean equal.
I was able to point out that DSD's Mom does a lot of fun things with DSD and takes DSD to get pics done every year as well, etc... that DSD isn't really missing out on things if she misses doing them with us... but if we plain don't do something because we didn't have DSD during that time, then our DD together would totally miss out on the experience as she only has us/our home... not two homes doing things for/with her.
DH did not see that at first, but after counseling has come around on a lot of things, this being one of them, thank goodness, as it has lifted some resentment/strain for me as I felt I wasn't able to have a full Mom life with my DD always trying to plan our whole worlds around EOW and it was driving me insane.
I am sorry that your DH feels that counseling should fall just to your shoulders.
But I do say you should still go on your own... it does help. I went on my own for awhile before DH came around to it and I think it did help strengthen my own communication skills to better tell DH what I was feeling and going through in a less accusatory way, which helped him not be defensive and actually listen to me...
As for your DSS... he does sound a little immature to me... but not bad in anyway. As for the party/having people over thing... I would say that is pretty normal, especially at his age. At 18 I know I certainly fought against any rules my parents had for me as I felt I was an adult and knew it all.
I wasn't trying to be disrespectful, but just to live my own life. I did end up moving out when I was 18 due to this.
As for the lying about work thing... he may have done it to spare your feelings. You are right you wouldn't have known for sure if he had work or not... but he may not have thought that far. He may have just thought, "hey I'd rather spend time with my GF this weekend than my Dad... but how do I tell Dad that?"
Especially if "visitation" is still being forced to strictly... I think I would have balked big time at 18 if my Dad was telling me I absolutely had to spend full weekends with him. I was barely home when I was 18 between work, activities, friends and BF.
I guess I'm trying to say... he is 18... you do have to understand he is technically an adult and fully allowed to have his own life. Pick your battles and rules that are age appropriate... such as no swearing in front of kids, if you are going to have friends over be respectful to the home and clean up after yourselves.
Good Luck with everything!