For Xiaomei Mi Max, what type of screen protector and case that you use, where to buy?
I use a tempered glass from Hitec. Keep in mind the face is actually slightly curved so you can either get the tempered glass which stops just before the black border around the screen o the one which continues until the edge but has a slight bubble on the left/right side of the screen (i.e. the bits which are curved).
For the case you'll probably need to buy online since not much in stock at shops other than the usual Goospery cases which range from $10-$20 depending on whether you buy from markets, SLS, pop up stores/kiosks or normal shops.
I personally alternate between a $15 Nilkin Frosted Shield case I bought online (highly recommended in terms of quality and strength since it brings some rigidity, is slim and textured, and also comes with free plastic screen protector) and a red $5 TPC one I ordered from Aliexpress (same bright red as Apple's official iPhone Product Red colour). Prices are approximate guesstimates from recollection.
Also consider getting an iRing. You may think you can handle the phone but the iRing makes it alot easier and also can stand up to watch on...