Yes you can. Most banks only give you penalty when you pay back all within less than 5 years or stated by the bank. Talk to your bank about it.

Like I say, the way you calculate interest shows that you're not familiar with housing loan interest at all....
mortgage interest is using amortising method.
excel PMT function:
(from excel help)
Calculates the payment for a loan based on constant payments and a constant interest rate.

Syntax

PMT(rate,nper,pv,fv,type)

For a more complete description of the arguments in PMT, see PV.

Rate   is the interest rate for the loan.

Nper   is the total number of payments for the loan.

Pv   is the present value, or the total amount that a series of future payments is worth now; also known as the principal.

Fv   is the future value, or a cash balance you want to attain after the last payment is made. If fv is omitted, it is assumed to be 0 (zero), that is, the future value of a loan is 0.

Type   is the number 0 (zero) or 1 and indicates when payments are due.
And according to your first post example, you'll be paying RM599.55 per month.
Logically if you've dumped in RM50k the next month your monthly repayment should reduced to RM300.07 but the fact is flexi doesn't work that way. You'll still have to pay monthly RM599.55 till you finish finish paying down your principal.

Hi... wanna ask something regarding Flexi vs Fixed Loan, & Daily vs Montly Rest...

My understanding (Flexi vs Fixed):
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Fixed Loan: for extra prepayment, it reduces your principle. Hence, it helps to reduce the interest
Flexi Loan: for extra prepayment, it will just park in your current account. And it "virtually" reduce your principle. Hence, it helps to reduce the interest (same as above), except that you can withdraw back the extra prepayment anytime, no charge (apart from other maintenance fees). Then the interest will be recalculated =
[ (the actual amount you owe bank - virtual prepayment you made) * interest rate / 365 ].

With my understanding above, if flexi n fixed loan come with a same rate, no way the fixed loan can be better than flexi loan, right? Or is there any other benefit on the fixed loan (let's say we omit the setup n montyly charges)?

Daily vs Montly Rest
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Everytime i see in the brochures, the bank will says smth like "interest is calculated on daily basis, so you can save on the interest". But isn't it with daily basis, the calculation will be in a Compound Interest way where you actually pay more interest instead of saving them? whereas for montly rest, it will be calculated once a month (net outstanding amt * interest rate / 365*30)?