Have you ever actually discussed it with him? What was the purpose of the discussion with this mentor?
1. As mentioned we are buying into the exorbitantly expensive frum lifestyle
Does he realize this contradiction? Has he addressed it and how?
It bothers me for a few reasons:
3. Like @iAm mentioned, my daughter is nearly 3 and I want her father davening to be a part of life.
4. It makes me not respect him, because I see him as teenager slacking off, not taking his responsibility to his family, to his parenting role seriously
Does he know that you are bothered for these two reasons? Does he realize that it is making you not respect him? Is your feeling that he is slacking off only due to the responsibility to the family or due to davening itself?
2. We (personally) have a lot of daven for (not just in a general world peace kind of way....)
5. I daven on occasion- but then it's not my mitzvah.
Could it be that the personal issues are partially the cause of his, in your words, slacking off? Maybe he is feeling a level of yi'ush.
If you have a lot to daven for why don't you daven more than occasionally? While women do not have the obligation to daven the specific nusach in the siddur they do most definitely have an obligation to daven since they too need hashem's protection. It is possible that if he sees a greater commitment on your part that he will be more committed as well.