1. Yes, but only those with accreditation. and you need a lot, really a lot.
[estimated: (junior, must) calculus I/II/III (III is multivariate), linear algebra, prob, stat, C++. (senior, very helpful for those less quantitative one. Must for any solid MFE.) at least a few more advanced math/stat course, like differential equation, numerical analysis, stochastic process, time series]
2. well, a 4.0 in LLB wont show your quantitative skill anyway.
3. both are weak signal. people will expect those with a law degree with better language skill (e.g. T > 105 / 110, and a much higher GRE AW). For the quantitative side, a 168+ (or at least 165+) GRE Q is a quite a basic requirement. (I really mean basic, i.e. you cant survive without that.)
4. this is a smaller concern.
P.S.
1. if you just care about career development in finance, instead of relocation to overseas, nor have any special academics interest in science, Law with application in Finance sounds to fit your background much better. Fighting for role on compliance, or corporate finance side is much more reasonable and is something that you can leverage your background much better.
(e.g. http://mlf.law.ox.ac.uk/, http://www.law.hku.hk/postgrad/llm/cfl/, and etc.....)