#1 You need to go back and add your location to your profile, Yes it make a differance where you live.
Here the way I do it, I add solid wood 2X's at the top and bottom of the walls. Any place there's gaps or a notch where a wire goes get filled in with high heat caulking for the small gaps, and expanding high heat foam on the big gaps.
I also add blocking along the middle of the wall.
Those old 2X's are going to be wider then a new 2X so your going to have to rip 2 X 6's or just add whatever thickness spacer you need.
A few things to concider.
Adding house wrap (Tyvek) between the wall studs to cut down on the drafts.
Getting rid of all that old steel pipe before it starts leaking.
Building the studs out so you can fit more insulation.
http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table
The very best way if you can afford it is to use foam not batts.
Here the way I do it, I add solid wood 2X's at the top and bottom of the walls. Any place there's gaps or a notch where a wire goes get filled in with high heat caulking for the small gaps, and expanding high heat foam on the big gaps.
I also add blocking along the middle of the wall.
Those old 2X's are going to be wider then a new 2X so your going to have to rip 2 X 6's or just add whatever thickness spacer you need.
A few things to concider.
Adding house wrap (Tyvek) between the wall studs to cut down on the drafts.
Getting rid of all that old steel pipe before it starts leaking.
Building the studs out so you can fit more insulation.
http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table
The very best way if you can afford it is to use foam not batts.