malindo RM400 per pax return, very limited ticket

I think you will love the food there haha! Ruins of St Paul nearby also got lots of yummy food e.g. durian ice cream and curry fish balls.

Yes, Macau accepts HKD/MOP and even RMB. Do change back or finish your MOP before going back to HK.

I am not able to answer questions 2 to 4 as I took a direct flight to Macau and bought my tickets from online agents here. Sorry ya 

5k is sufficient. Bring 6k to be safe because exchanging money in HK is more expensive than exchanging MYR for HKD in Malaysia. My overall spent is RM1.2k for 5 days 4 nights perperson (includes some shopping)

A few things to note.

1) Meals portion is big for the price you pay. If you allocate 50HKD per person meal, more than enough unless you go to more atas restaurant. (Some meals i share with GF)
For example,
Beef Noodles = 34hkd
Pork Loin Breakfast - 38hkd
Hot Pot Dinner - 66HKD  (Shared)
Pork Knuckle Noodles - 45HKD
Street Food Supper - 35HKD (Shared)

2) Disneyland meals are more expensive, paid 120HKD for pork chop cheese baked rice. Comes with 2x big porkchop and ALOT of rice. Shared meal with GF.

3) Transport use Octopus card. (Touch & GO)
Spent approx 300hkd for train & public transport.
50HKD deposit (Refundable upon returning the card) Whatever balance amount you didnt use is also refundable.

Anybody found cheap AA ticket to HK?