1] How to prolong his custody till conviction gets over, as he belong to different state and can run away once freed on bail?
He cannot be denied the right for bail, if he once again escapes after coming out on bail, he will be considered to have jumped bail and on his arrest he may be remanded. his problem will be of the police.
2] Can some condition impose on guaranteer like post 50% of amount submission in court only the bail plea should be accepted otherwise it should get rejected?
Yes this condition can be imposed while granting him bail.
3] My wife is still under influence of this fraud man and has not returned home since his arrest and I'm aware of her whereabouts but couldn't contact her as she has filed wrong complaints against me of hitting her in local P.S, even she is not contacting her family members as well. How can I protect myself and also protect her once this godman can be out on bail then he can use her against me? My girl child of 2.5 years age is presently with me.
You have to secure evidence to file any case against her.
4] Can polygraphy be applied on him to find where he has invested the money? What is the process to get permission?
No, no at least officially or legally.
.5] Can Police weaken case by any means while filing the chargesheet, I've shared all documentary proofs of account transferrs and forged documents of culprit?
Depends on the graft received by them.
6] Should I higher a lawyer to fight my case post chargesheeted when there is a PP, as what I've experienced during Session and High court hearing, the lawyer I hired is of no use as he spoken the least?
No, not necessary. He can only assist the PP and can do nothing on it.
7] Can he get bail again after charge sheet get filed by session court or high court? What ground should be the best other than "huge amount involved" and "no recovery from him till date" to stop his release on bail?
Request the court to impose condition for granting him bail.
8] How to make my case very strong against him, can I ask other cheated person also to file similiar case against him?
Yes you can gather support to your cause that way.