1. if you are talking about standard TSOP48, I just use hot air. I have a cheap satioon that has ben working flawlessly for over 2 years, maybe more (I think I posted when I bought it, so a search may turn up price, details) It is a YIHUA 862D. anything with 862D in the name is probably exact same thing with different clothes on. The soldering Iron I wasn't concerned about, as I have a good Micron, but actually once I bought some needle point tips is really a good iron... well it does the job nicely but I have never used what an industry guy might call a "good iron" that costs a lot!
2. I use 1200grit wet&dry sand paper (no water) and take it really easy. It is a bit slow and takes a while but works fine. I am hesitant to get into it with a dremel and sandpaper or buff bit.. Be especially careful with some microSD cards that have a circuit trace running along the edge. if you rub/sand through it, you could be breaking a needed circuit.
If you have a pinout, you don't need to remove all the coating. most times I do it if it is a new pinout, or I want to photograph it. But a customers monolith, it is just unnecessary work and added time and abuse for something to go wrong.
I would NOT use a scalpel. I understand how you could do it, but 1 slip and it is all over. some circuit traces are remarkably easy to pull off the board.
tips were posted a while ago and went into detail for this I think under "soldering monoliths"
things like a good microscope, good solder and flux, and above all - practice.
trying out methods on customers devices is not practice, it is recklessness
