1)Effect of low price guarantee

In low price guarantee what happens is Retailer agrees to match the price of a competitor if the customer finds the item cheaper elsewhere.
Because of this actions there will certainly psychological benefits to offering a price match or offering to beat competitor prices. It's a marketing thing. It's a customer service thing. It's a loyalty thing. It's part of your value proposition, if you offer such a guarantee.

Low price guatantee reduces compitition,penalise inattentive retailers and it provide false sense of security

2)If a group of sellers could form a cartel, they would set the quantity and price in the way a monopolist seller would set price and quantity in which marginal revenue equals to marginal cost

3)

Price discrimination is possible under the following conditions:

The seller must have some control over the supply of thier product. Such monopoly power is essential to discriminate the price.

The seller should be able to divide the market into at least two sub-markets

The price-elasticity of the product must be different in different markets. Therefore, the monopolist can set a high price for those buyers whose price-elasticity of demand for the product is less than 1. In simple words, even if the seller increases the price, such buyers do not reduce the purchase volume.

Buyers from the low-priced market should not be able to sell the product to buyers from the high-priced market.