1 - you're not going to experience true withdrawals unless you are using daily for around two weeks. with the dosages you're using they'll be minimal. otherwise, you may feel some rebound effects, such as insomnia, increased pain over the body, sweats, little nausea, similar to wd's, but not to the severity as being dependent.
2 - i think that's a totally acceptable amount. a lot of people on here wish they were still able to take such small doses and experience a lovely high. don't go upping your dose just on account of you feeling it's inadequate! hell, it's all the more reason to keep it as low as possible as long as possible, that way when you have to come off the wd's and PAWS are going to be a walk in the park compared to something like an 80mg habit
3 - i think they just help with the absorption, thus increasing the initial effects. i could be wrong so don't quote me on that. i know they increase amphetamine's effects.