My 20s is all about reaching millionaire in MYR by 30 and dating to prepare for marriage. 

If I accidentally marry a gold digger and divorced then yea, my 20s' lifestyle is gonna repeat again...
Hard to explain to my family lah... let me try dating the Shanghai girl and see how things go. At least she's in SG and err doesn't look like a gold digger. In fact she told me you would hope you won't meet a gold digger... 

I won't be buying a house until I get married/almost married under the fiance scheme from HDB.

I think by 30 I would be close to marriage and looking for houses seriously with my partner

The mortgage should be liability, the house is your asset. As you pay off your mortgage gradually, the asset side increases and the liability side decreases.

I haven't checked the terms and conditions for housing loans/mortgages in SG yet though. Will need to talk to my girl on that matter as well.

https://www.hdb.gov.sg/residential/buying-a...es-and-families

Under the HDB Fiancee Scheme, one of them must be Singaporean and the other can be PR or Sporean.

For new HDB flats and Prime location resale flats, if I am a PR I will need to pay 10k SGD to the SG government as "compensation" which can be clawed back with a grant when I become a Sporean in the future.

Both new flats and Prime resale flats are subject to income cap of 14k SGD a month, which I will likely exceed if I work at a hedge fund after my PhD...

Next up the rank is executive condo, EC in short. That one has similar citizenship requirement but no more claw-back grants from the SG government (they only subsidize the land price). Income cap 16k SGD a month... If my Shanghai girl still works probably our combined income will exceed this limit as well... So,

One level above is the condominium... No subsidies at all from SG government... Super expensive... But the quality is probably the best, got private pool, gym, BBQ pit etc.

There is another level above condo, it's called landed property, like bungalows and good class bungalows (GCBs) but uhm unless you have significant contribution to SG and a Sporean, you won't get to buy one. And it's super super expensive. One GCB can fetch 20-50 million SGD depending on location.