Thank you Jannis for your prompt reply.
With your help, I managed to resolve issues 2 & 3 
With issue 1, I'm having the JSON issue on 7.2 SP10 and also IdM 8.0(when I'm consuming rest services from v72alpha) I haven't tried REST version 2 yet.
Hopefully there is patch soon to address this JSON issue with v72alpha.
Cheers!
KV