In which order does the covalent character change in $LiCl, BeCl_2, BCl_3, CCl_4$?

Which of the following is the correct decreasing order of the melting points of calcium halides?

According to Fajan's rule,electrovalent bond formation is favoured by

The correct order of the increasing ionic character is

How would you explain the following observations?
$(i)$ $BeO$ is almost insoluble but $BeSO_4$ is soluble in water.
$(ii)$ $BaO$ is soluble but $BaSO_4$ is insoluble in water.
$(iii)$ $LiI$ is more soluble than $KI$ in ethanol.

Arrange the following in increasing order of their covalent character.
$CaF_{2}$,$CaCl_{2}$,$CaBr_{2}$,$CaI_{2}$
Choose the correct answer from the options given below.