first i'd like to say i'm new to step-parenting (about 9-10 months in)... and parenting in general, no children of my own though we would like to have a couple in the future but i've gotten fairly adjusted to it and i love my stepkids! they are great kids, two boys age 4 and 6. they stay with us every other weekend. much less than we would like but we hope to change this. we make the most of our time. it is difficult for my husband as he wishes he could be more involved in how they are raised. he does not agree with many things his ex-wife does/teaches his kids, but less than a week per month is not a lot of time to teach values to the kids and reinforce them, as they will just be told the opposite when they go home.

anyways, here are some things going on that seem off color to me that i'm worried about - but i am new (really kind of clueless) to parenting, and i need another perspective.

1. the oldest gets upset VERY easily, and will get withdrawn yet overly agressive if something bothers him. (sulking for 30+ minutes, or more often getting red-faced, yelling, and hitting (for example, if his brother is playing with a toy that he wants or if he is served milk instead of soda) - of course this could just be what 6 year olds do

2. they are hungry EVERY time they come over, begging for food. i'm always shocked and like, of course you can have food! i now make a point to ask if they ate dinner/lunch, and the answer is always no. the 6 year old says things like "we went home but we didnt have time to eat anything cause we forgot" "mom said dad would buy us happy meals" "i ate an apple at school but didnt get any dinner" situations always seem to come up that prevents them from eating for 4, 5, 6, even 8 hours.

3. they are NEVER dressed for the weather. throughout the winter they were sent to our house with coats only ONCE. every other time it was t-shirts and shorts in 30 degree weather! it puzzles me.

4. she pulls them out of school a lot. nearly every time they come over, one of the kids missed school that day or she is taking them out on monday for this or that.

5. they are sick a lot. the 6 year old always has a cough that is never cured. often she sends a pouch with a variety of medicines, cough syrup, triaminic cough strips, allergy medicine, various nose sprays, ointments, etc. (what do they need all this for?!?)
their mom does not follow the instructions on the medicine bottle. she doesn't make them take what theyre supposed to and they take the wrong meds. this weekend my SS gave me a bottle of medicine saying "im supposed to take this for my cough". it was prescribed to my other SS. theyres always something like this going on.

6. she pushes atheism on them. it isn't wrong to be atheist if you want but little kids shouldnt be outright told that religion is hogwash and be insulting to others' beliefs. (spirituality is very important to me but i do not push it on them, i just want to teach them to be tolerant of all people). the six year old has a rehearsed script about it, my husband mentioned god and he said "you can believe in that if you want but it isn't real" or something to that effect

7. their mom just generally doesn't seem to care about them: she will openly say "i put them to bed early, they were so annoying" and stuff like that. she hugs the younger one goodbye and says i love you but i have never heard her say i love you to the older one or seen her hug him

8. over the kids' fall break she went to the beach and they stayed with us, she uses time away from them as her fun time - every weekend when they are here she and her boyfriend are on a vacation or out at some fair or this or that and change plans last minute - like texting to say "we won't be back till monday night, can you keep them an extra day?" because she is so spontaneous and unplanned... usually she wont even come get them, we drop them off at their grandparents' house. she's always saying "you can pick them up at such and such". only once or twice have we picked them up from her directly and she's picked them up. (we are all civil so that's not the issue)

9. they cuss a lot, calling each other b word, n word, and we let them know they can't say those things at our house. i guess they don't get in trouble for it at home. (for example: SS said he didn't know those words were bad and asked why he was in trouble)

so my question, is this normal behavior or does any of this stand out to you? we don't really know what is going on at mom's house.
my hubby and i are considering asking her to let them come to us every weekend, and we think she will probably be fine with this. we do want majority of the custody someday - i know it is hard to take away kids from the mother and we have no proof, really, and they are not being physically abused as far as being hit or anything. is it possible for them to live with us and how does this work in a court? we want them to see her but we feel our house is a better environment for most of their time.

how would we go about getting them to live with us, should we, and does it sound like they have a bad environment at home?
how do i know if they're being treated well at home? what would you do in this position?