Which is the suitable reagent for the above reaction?

For the following reactions,the major products are shown: $H_2C=CH-CH=CH_2$ $\xrightarrow[0^\circ C]{HBr} CH_2=CH-CH(Br)-CH_3$ $\xrightarrow{25^\circ C} Br-CH_2-CH=CH-CH_3$. These provide an example of $1$ control at low temperature and $2$ control at higher temperature.

Which hydrogen in compound $(E)$ is easily replaceable during bromination reaction in the presence of light?
$CH_3 - CH_2 - CH = CH_2$
$(E)$

The product $(P)$ of the following reaction is:

$CH_3-C(CH_3)=CH_2$ $\xrightarrow[R_2O_2]{HBr} X$ $\xrightarrow{CH_3ONa} Y$; $X$ and $Y$ are:

The decreasing order of reactivity of the following alkenes towards $HBr$ addition is:
$(I) \ CH_3-CH=CH_2$
$(II) \ CF_3-CH=CH_2$
$(III) \ MeOCH=CH_2$
$(IV) \ CH_3-CO-CH=CH_2$