If you want to show your sincerity to ICA, don't do any of the above as you will be initiating them after your initial application. They no longer work anyway due to the blatant abuse in years gone by. About the only way they would have any bearing on anything is if you had been doing them without an ulterior motive for a number of years prior to making the decision to apply for PR. Basically, if you are not altruistic by nature, don't waste your time as it's a useless endeavor thanks to those who came before you and royally burned those bridges for everybody else.
Additionally, even if you marry the girl, you need to be (anecdotally, anyway) married around 2 years as you have already made one application as a single individual so a "New" marriage will look like a "marriage of convenience". The ICA has see far too many of them over the years so now they are pretty clued in and tend to err on the side a caution (hence the 2 years of marriage). This can possibly be shortened to bit longer than one year if the spouse can produce offspring around the one year anniversary (one tends to be a bit more committed once there are children involved).
Oh, one other thing that ICA is worried about is the fact that a high percentage of East-West marriages never make it past 2 years so they are protective of their womenfolk as they are the future baby ovens for NS men. (It is what it is..) The gahment is very pragmatic and has to consider everything for the propagation of future Singaporeans & NS Men.
Yes, This board had a very high percentage of long-term East-West marriages that have withstood the test of time (most of us have offspring as well). In fact most of the long timers here are of that type. Myself included.