For Maybankard2Card AmEx is straightforward, no categories basis.
So long the transactions are processed during weekends, you will get 5% rebate.

As for your first question on the online transaction, you didn't quote the full sentence.
"However it is reported that some online transactions on weekends DO NOT earn the 5% cash back as it depends on the timing the merchant processes the transaction."

-Some merchants (for e.g. Dell) don't process during weekends, you may make your order on Saturday but the payment will only go through on weekdays. So you will not be entitled for 5% rebate.

On every good example is Dell online purchase. They process the transaction on weekdays, thus you are not getting the 5% even if you paid on a weekend.

From my experience, you will get 5% rebate with Astro. No experience with the rest.

  Definitely not true. Very typical though and this doesn't only apply to Maybank staff.

Don't worry. I'm very confident with my previous answer as I've been holding this card for more than 2 years. As a matter of fact, I was one of the first to get this card here... only days after this card was launched 
Which part that you doubt ?

no need to worry...all of us here use it and petrol is always there for 5% if it's used on weekends

Nothing to worry. This is the only card that I don't need to monitor so long my transaction is processed during weekends. I'll definitely get 5% rebate.

My last week's purchase using PayPal went through, paid at around on last Saturday's 8.00 p.m.

Reflected on my bill on 25th. Yeay, 5% rebate.

Can, 3 months of latest payslip is sufficient.

Unlikely the reasons you mention. More likely:
1) You have no previous credit history (credit card, loan, hire purchase)
2) You have credit history, and the bank thinks you are over-credit.
3) You have credit history, but payment not good. Delay, non-payment, etc.

we cannot understand how bankers evaluate for approval.
Dont get upset about it, there are many cc around.
I have car loan with maybank yet they rejected my cc request.
And worse still i applied for ocbc tit a week later. And approved wilt cl of 69500.
Can u belive this. cannot really understand them. move on

Don't Give Up, Try Againlah... I got My MBB 2Cards on the 3rd Attempt Same As Well with My Citi's CC (although I have Account with Both of Them) 
I think the UOB One Card is the Most EZ get CC, many ppl have this card at here ( I X have Any Account with UOB)...

i myself had no record as well originally - just started working.

Apply with OCBC Ti - Rejected
Re-apply - Rejected
Apply with M2K - Approved on the spot
Apply with CTB - Approved

now don't even bother to apply for OCBC Ti

Currently, You X have Credit Card...???
I been tried to Apply MBB 2Cards since 2011, Every Year Submit My Apps Once  I have try 3 times, MBB 2 Card is My Final & the Last CC...
I have Apply OCBC Tit. 2x also kena Tendang...

FYI, I Never have Any CC before 2011, Now I Got 13 Credit Cards ALL Which are 3 RHB, 3 HSBC, 2 Citi, 2 UOB, 1 HLB, 1 SCB, 1 MBB 
Now Kena Potong Half of It, if Not nanti got Dizzy with GST...

best part is OCBC still dare to email me about applying the same blardy card.

I replied "I've been rejected twice"

no reply after that