I always walk in n out, numerous time without informing, they usually can recognize me but for safety purpose in case the receptionist change shift, bring ur sign-in slip with u

* Smoking lounge is few door away from PPL KLIA 

The max I stayed in PPL is 7 hours (overnight), the receptionist even remind me that I don't overslept and miss my flight 

depends on the counter staff, some will ask for your boarding pass, some no

I have mentioned before in this thread, most of the time you do not need to show boarding pass but they may need some form of identification.

For example:

my Maybank VI and Priority Pass Membership card no need whatsoever identification or boarding pass.

if use my Alliance Privilege Banking Debit card at KLIA2, need to show NRIC as the card has no name printed on it.

For CIMB where you use voucher, PPL will ask for your boarding pass as they need to photocopy it or scan it to forward to CIMB Bank!