What is Charging Voltage & charging current limit setting for 12Volt battery with 75Ah............

the reference is the battery voltage and the ampere hour rating. These are already specified. Charging will depend on your available charger. The voltage should be within tolerable level of the battery (12-14v dc). Your charger should be tuned to the voltage range of your battery. You can only play around with the time and current if your charger is flexible with ranges of current (slow,normal fast/boost).

Mathematically, you can derive the charging time if you have a known charger rating, by the following approach:
If you are charging with a voltage source very close to the battery rating say 12-14v, for a charger of 75A rating , you will charge the battery in 1 hour. If your charger is of lower rating,then divide the amperhour rating of the battery with current which your charger can deliver to get the time it will take. Eg 30A will take 2.3hrs to charge the battery.
It actually depends on your available charger. If your charger is of lower capacity,you have a longer charging period.
If your charger is above the battery rating,it will still take shorter time to charge the battery and you may run the risk of over charging the battery. Consideration should also be given to the effect of over charging on battery life.This is just the abc... of it. Cheers

The battery manufacturer's manual for that specific battery will give the proper settings for float and equalizing charges.

The comment of Adam is the most appropriate recommendation to follow. Refer to he manufacturer who designed and engineered the production of that specific type of battery. Following their recommendation will provide you the correct operation and longer life of your battery.

the battery rating is in Ampere hour. It is usually written on the battery or the package. If not sure,ask questions before you buy or consult the battery manufacturers manual.

We here in my country batteries for UPS, mainly with 190 & 140 written on it respectively according to their sizes. How can you deduce ampere hours from that?

Muneeb, I wouldn't know exactly what those figures stand for with out any units. If your UPS has a standard rating,then you should be able to know its battery capacity , the length of time it should attain full charge and last when powering a rated load. Having said that, it is best to find out from your UPS manual what its battery capacity is. There is no doubt that batteries are rated in amperehour. However, some manufacturers may want to chose a different configuration in identifying their battery. Please always refer to manuals.