[Q] New in Rooting and install Custom Roms - SM -G900H topic

Its been long time,
Still waiting for official lolipop update,
There is no info about it.
Now I'm thinking to root and wana enjoy the customization in custom roms.
I have some question about safety
Yea I know I will lose warranty,
I did root my last s3 I enjoyed lot.
But in s3 there was way to relock boot loader,
Is its same as s5?
I mean
Q.1 is there any way to get warranty or relock?

Q.2 In case any hardware problem will Samsung service center will detect warranty info or something?

Q.3 I mainly installing custom rom because Im stock lover, is cynogen mod completely work? Also on screen button there?

Have more question but not in mind at that time.

I would be much thank you if you help me..
Thanks in advance.. :)

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