I'd like to just respond to the tipping question (q 1-4, also question 7). You'll have lots of responses to questions 5 and 6 so I"ll defer to the others on this.

In principle Singapore is a no tipping country. It has been government policy to discourage it and for typical everyday transactions service people perform without expecting a tip (as it's you're first visit to Sing, you will see that 99% of cab drivers will charge per the meter and return the change to the nearest five or ten cents). Restaurants and hotels will impose a service charge on the bill. Having said that, there has been talk in the papers that maybe the tipping policy should be rethought as typical Singapore service can be indifferent and that a direct tip might improve things.

Given this background, you're going to have an exceptional experience between JetQuay and the St Regis - btw I'd consider St Regis 6 star as many of the hotels are at 5 star level but St Regis should be at even higher service levels than that. Other FT'ers should weigh in on this tipping question as there are exceptions to every policy (even in Singapore) and if ever there was a situation that deserve an exception, yours is it. My own thought on this is that the service people you run into won't be expecting a tip and will not behave badly if they don't get one but would take it if it's offered.

On question 7, the ability to leave luggage with the concierge is quite common and typical just about every place in Asia (if not everywhere, period). I see no reason why the St Regis wouldn't do this for you.