Sounds like you're in the pits of the four month sleep regression. Formula is no guarantee of sleep. It can make sleep worse as it's harder to digest than human milk so can give babies pain.
Formula can cause problems.
Or it may not.
Your body will hopefully regulate to produce less milk if your baby accepts formula. Your baby may love the bottle because it's easier to take more and so develop a "bottle preference" or they may be absolutely fine. Look up "Paced feeding" to ensure that baby doesn't overfeed.
There's no "best" formula. They all have to contain the same essential ingredients.
Aptamil are the most expensive and the market leaders. They are no better than any other but the packaging is space age so screams "science".
Stage 1 all the way.
There is literally no reason to feed anything other than stage 1. Stages 2 and 3 were created simply to get around the advertising laws saying it's illegal to advertise or promote formula for babies less than 6 months.
Dishwasher.
Sterilise before use
Make up formula properly. Don't use a prep machine as the "hot shot" is inadequate to kill the bacteria in the powder.
If money really isn't a concern then for one bottle a day I would simply buy readymade.
Discard any made up formula after 2 hrs or 1 hr if the bottle has been drunk from.
Making up bottles to fridge is a dangerous and outdated practice. The risk is as the bottles cool they spend a lot of time in a "dangerous" temp where bacteria multiply. If you insist on doing this then you need to rapid cool. Place the made up bottle inter ice cold running water until the formula is cold and then fridge it.
Bottle wise. Lots of breastfed babies are pickles at accepting a bottle. Try a REALLY cheap teat. Like an ownbrand from a supermarket. It's a lot more flexible so more similar to the nipple baby's used to.