What is the use of plants with desired characters?

Plants having similar genotypes produced by plant breeding are called:

Where was $IR-8$ developed?

Consider the following four measures $(1-4)$ that could be taken to successfully grow chickpea in an area where bacterial blight disease is common.
$(1)$ Spray with Bordeaux mixture
$(2)$ Control of the insect vector of the disease pathogen
$(3)$ Use of only disease-free seeds
$(4)$ Use of varieties resistant to the disease
Which two of the above measures can control the disease?

What does hybrid vigor (heterosis) involve?

Himgiri is a variety of ......