mobile

Hi just got my new phone Galaxy S5 G900V from Verizon and I have some question.
I’m on official ROM 4.4.2 NCG rooted. I tried official 5.0 OC4 but I didn’t have root and some of my games ware lagging so I switched back to 4.4.2.

1- Which do you think is the best official ROM? Should I stay on 4.4.2 or update to 4.4.4

2- When I charge my phone and it reach 100% often as soon as I disconnect the charger the battery drop by 5-10% so I plug in again for it to reach 100%. Any idea why this happen? Also I notice the first 50% drop much faster than the last 50% is this normal?

3- Is there anyway to force my phone to use H+ only?
I don’t live in US and the best band here is HSDPA+ at work my old Atrix 4G had no problem connecting to H+ but my new S5 constantly drop data connection and the icon on the notification bar constantly change between 3G / H / H+ with the little arrows mostly gray. In network mod my phone say GSM/WCDMA/LTE and if I try to change it, it give only 3 option Global, LTE/CDMA and GSM/ UMTS and none of them is selected. I used Global when on lollipop and I had the same data connection problem.

4- I’m using a case which is plastic but it has aluminum back. Can this metal back cover interfere in signal reception and /or wireless charging? I plan to install one of those ultra slim wirelesses charging receiver.

Thanks

p.s. Sorry for my bad English.