I think it is really important to separate out 'house rules' from 'child improvement projects'. House rules are a reasonable expectation, they are based on specific behaviours (not personality issues), and it is possible to get results. Child improvement projects are not going to get you anywhere and are just going to lead to conflict and unhappiness all around.
What are the rules that you and your DP can agree on? You have an absolute right to have a say in how things are done in your home, and especially around areas that directly affect you. You will probbaly get more cooperation if you focus on a few very specific areas and how they impact on family life, rather than trying to change all the kids' habits at once.
I chose the areas that directly impacted on me, and put down my foot there. I insisted on no mobile phones at the table, and that we eat at the table, not all over the house, for instance, and we expect everyone to be given a chance to talk and be listened to. What they do elsewhere is not my concern, much as I would love to think that they would be well-mannered everywhere they go - but at our family table, there are rules. These rules are not as strict as those I enforce with my own DD - for my own sanity, I have accepted that my DSCs manners will not be what I'd expect from my own DD. That doesn't mean I have to put up with bad manners altogether. In the rest of the house/life, it is the same. They can make a filthy mess of their rooms, but shared areas have to be clean - and if their rooms begin to stink or become a fire hazard, they need to bring them back within inoffensive limits. And so on...
Like notdisney has suggested - establish what your own boundaries are and stick to them, clearly and consistently. Forget about improving the kids - just focus on making life together more pleasant for all.
(I think there was a similar thread on here just last week, I think - you might have a look back at the responses to that, too.)