floyd rose is possible.
but you need to rout it for a typical fender-like 2-point and not for modern day floyd rose deeper routing (i would assume common sense would account for this, which is to say most ppl dont have common sense since they say you cant put floyd rose on an SG).
even take a look at older fender strats with 2-point trems, those can also be retro-fitted with floyd roses.
below is my 80s Gibson SG, that came from the factory fitted with a floyd.
as for bigsby, you can put that on anytime.
but for me, bigsby is a pain in the ass.
i would rather re-string 10 floyd rose guitars than 1 with a bigsby.
Its the tremolo block. As with all FR / vintage style trems the blocks are where the ends of the strings reside in and springs are attached to at the back cavity.
FR is able to get in singapore thats for sure, depending on price, arund 300+? for bigsby you'll have to order online and needs to be shipped into sg, which adds shipping cost to the equation. this answer is very rough in terms of detail, but it gets you the idea.:-D