Centrifugal pumps are typically the most cost-effective. Positive displacement pumps are typically more efficient than centrifugal pumps however, this advantage is usually outweighed by higher maintenance costs.
Water pumps work differently depending on the model and brand. Some of the brands available in Nepal are: Showfou, Ingco, Crompton, Daewoo, MPT, Grundfos, Sarvo etc.
Yes, doing this is completely fine. Additionally, you will gain the advantage of being able to remove undesirable impurities like mud or salt.
Which pump you need depends on how much water you need to pump, how high you need to pump, how fast you need to pump and how dirty the water is.
You can buy variety of water pump from fatafatsewa.com.