If worse comes to worse, you can contact Remington and I am sure they can provide you with a magazine. If you have a local gun shop however, odds are good they have one on hand or could order one for you.
If that fails, or you would rather order online, search it in Google.
The 7mm Ultra Mag is a Remington cartridge. THE model 70 is a Winchester rifle. Winchester does not chamber the Model 70 For the 7mm Rem. Ultra Mag cartridge.
I shouldgest buying a cleaning snake, the snake for the 7mm mag. fits the .270 as well, it will give you the cleanest gun you have ever seen.
How much is a savage 7mm
Value about $300-500, depending on condition, and the exact model. There were Several Mdl 111's in 7mm Mag.
9.5
100-500 depending on specifics
Depends on the model and condition, but about $300-$375.
1968
Should be 1 in 9.25
It should be marked on the barrel. There are other 7mm rounds besides the 7mm Mag.
You must call S&W with the serial number to find out if it was subject to a recall.
Proofhouse.com has Winchester sn data