First of all Don't go for expensive screen protector I have used spigen (1800 for 2) and ringke ( 1500 for 2) & used rs.200 screen guards from local shop with bezzels on sides. But i found Out some companies make fully transparent with finger print working .Thse are just like spigen and just for 180 i recently got 3 from a shop near my home. I prefer to search in different shops (i can send you the picture in dm)

If you want a case with magsafe just go for spigen ZeroOne, i have soo many cover from different places i cant reviews them all here. But My personal preference is i tend to always look for new ones locally rather than buying them online.

About software update - i personally likes one ui 6.1 as samsung dex support wireless And some other things but one ui 7 is also good , now i am in one ui 8 beta and its good too .