Re your stallion, I don't know what 'typical stallion manners' are(they're all so different & generally only had to do with well trained ones), but that he's been an untrained 'pasture pet' running with mares for 8 years(?), I can guess he may be a bit lacking in manners. And it sounds like you're not confident. I don't personally have much experience at all with gelding older horses. I do believe they can 'settle down' a bit more, even after they've had lots of experience being 'a stallion'. BUT it's not going to teach him 'manners' - you have to do that. And if he's lived naturally in a herd with mares all his life, chances are, his 'manners' with them are pretty good, and he won't forget what 'training' he's had there either, but there may be other learned behaviours he has which may be problematic for you, before & after the hormones have left the building. It's more about your skill level and confidence than him, most likely. I think you just need to advertise him to an experienced, confident home & disclose that he's been a breeding stallion.
With your filly, it sounds to me like perhaps she hasn't been taught to lunge & you don't know how to teach her. But not enough info to be sure. What do you mean by 'standoffish' and what do you mean by 'needing to re-establish respect'? How do you envision lunging her is going to help with that & what 'manners' are you trying to teach with lunging? 'Respect' is one of those very subjective, ambiguous terms...
Sounds like she & you could do with some lessons - I'd suggest you get someone experienced to put the basics onto her, then give you some lessons, to ensure you have a better idea how to keep it up/improve her training.
If she's 'standoffish' generally, I'd want to make a point of becoming a Good Thing in her life, have her WANT to hang out with you. If she 'lacks respect' and doesn't yield to pressure, she needs to be taught to yield well, *BEFORE* thinking about lunging her, and when she understands how to yield, then you can teach her some 'manners' so that she can learn to be 'respectful'.
So... she should be yielding well, leading & driving first, on BOTH sides(just because a horse learns something in one way doesn't mean it transfers to other situations/sides etc - they don't generalise well), then 'lunging' is just a matter of doing that at an increased distance. If she does it well on a short lead on both sides, no reason why she couldn't do it further away, but maybe she hasn't made the connection, you've made too abrupt changes for her, or she doesn't drive well up close, etc. I suspect it's training, BUT it's also worth considering she may have a physical problem which makes circling in one direction uncomfortable for her.