VivianChaste
For long term wear, I'd recommend ones that are custom made, like My-Steel, Neosteel, or even Fancy Steel. They all offer ones that may be suitable for your situation as well.
Thigh bands... they aren't really necessary, but if you want to have thigh bands in mind, when you choose a chastity belt, get at least two d-rings attached to its each sides and / or one additional d-ring on crotch area (which would be used for chains that connects chastity belt and thigh bands)
Chastity bra is kind of another addition too if you want additional security but I heard it is hard to manage wearing it in daily life, especially in hot weather.
Solo keyholding is kind of hard without using a timed lockbox, I'd recommend having a keyholder you can 100% trust, if possible. 24/7 wear does still require periodic release for cleaning and maintaining hygiene of both body and belt.
There may not be much differences in clothing if you choose to only wear a belt, but if you want to add thigh bands, you will have to wear skirts / dresses only.
VivianChaste lifestyle, i could schedule my day to day to make myself a more proper lady or not!
Can you clarify more about being a "proper lady"? There are no single way to define "proper lady", when it comes to lifestyle, since it is very subjective aspect.