ATTIC INSULATION

Hi, guys. I'm looking for some advice about insulating. My question is a long one so I'll break it down. I have a finnished attic with a knee'ed interieor wall. This creates a a storage space on each side of the house facing the gutters and a small space above where the peak is. LOng story short i get bad ice damming on the side that gets no sun during the winter time and i have very little insulation at thei time. MY house is 60 years old and it has tar paper backed insulation of some sort which is now about 2 inches thick on the walls and the ceiling joists in the storage space. I have peak and roof vents but these are above the knee of the interieor wall and this basically creates a dead air space in the strage areas. Also I have no overhangs and there fore no soffets for vents. My roof ends flush with the walls. I plan to use batting on the ceiling of the peak space but here's my questions

guy from lowes recomended this. scab rafters with 2x4s and insulate the rafters and side walls with highest r value fiberglass then cover with 6 mil plastic as a vapor barrier thus making the storage space a "warm" space... treat it like an interior space sort of though unheated. I planned to use r19 then on interior walls ceiling joists for added insulation.
My original plan was to scab wall studs and ceiling joists with

2x4s and insulate with highest r value possible. to increse air circulation I was going to cut holes into exterior side walls and install vents... probably ones used for shed peak vents. I would keep this a cold space with this plan and not insulate the rafters.

Which plan do you guys think I should use? other important information. The side that i plan on insulating this year has ceilings for the 2 hottest rooms of the house... kitchen and bathroom. I wanna keep it as a storage room and therefore i will be keeping some form of decking in there. also, the chimney runs through this and is another source of heat for the space.

Thanks in advance for the help

phil