Hi, allow me to give you a brief of what to expect...I can't guarantee that the information will still be correct when you travel in June.
Q1. The advance menu that you receive is called "Book the Cook". It consists of local Singaporean or international favourites that you may want to have onboard. You basically order the dish you want with your reservations and that particular dish will be uplifted for you when you travel. However, if you choose not to use this service, then you can choose from the inflight menu when you board the flight. It is really up to you. With "Book the Cook" you decide exactly what you want to eat on that flight and do not have to worry that the menu on that flight might not be to your liking. It is something like ordering special meals, just that this particular one has lobster termidor or sharks fin etc. Order for Book the Cook has to be more than 24 hrs in advance (or earlier). light Snacks are available for first and raffles class at anytime during the flight. These may include sandwiches, crackers or soup (depending on the route and flight).
Q2. All 747-400s come with the Ultimo seats in raffles class. However there are two kinds of first class configuration in the 744 fleet (12 skysuites or 16 first class seats in 2x2 config). Currently, LAX-NRT-SIN flight should be operated by the aircraft with skysuites in first class. There might be last minute changes due to operational reasons. It will take a while to install the Spacebed seats in its entire fleet. If you get it, I would say you are helluva lucky guy!
Q3. In Singapore Changi Airport, so long as you hold a first or raffles class boarding pass, you are automatically granted access to the Silver Kris Lounge. However, things might be different in certain stations. You can always ask the SQ ground staff in LAX if you can go to the lounge (if I were you, I would leave out the fact that yours is a redemption ticket).
Q4. They are still testing out the Internet PTVs I think....
Hope this info helps. Again I stress that the situation might change come June...or they may not operate the 744 into LAX anymore .... so be prepared.
There's always a better way to fly...