If it is truly a rifle (spiral lines on the inside of the barrel) then no. BB guns are smoothbore. The hard steel BB will usually stick in the rifled barrel, where a soft lead pellet will squeeze into the rifling. There are very few guns made to shoot both BBs and pellets- but they are marked that way.
In a break barrel and pump rifle it located directly behind the barrel in a large tube. Rifles that use C02 usually hold the C02 bottle under the barrel.
No: break barrel rifles are designed to use a "Spring or Nito Gas" piston. C02 doesn't require a break barrel design. BUT Spring designed are much stronger than C02 systems
Only One no more. It's a break barrel rifle you only have to cock it once for each shot.
It depends.. if you have a carbine length barrel and will be using it on a rifle with a carbine length barrel, then yes. If you took it from a rifle with a rifle length barrel, and are putting it on a rifle with a carbine length barrel, then it won't function properly.
Pull it through the barrel
You can't. You will have to sell your old air gun, then use the money towards a new PCP air rifle.
No. Only use what is stamed on the barrel.
Mis-use
It may work but it is not normally recommended because the shock from a pellet rifle is different from a regular firearm and it been known to jar loose the glass in a rimfire scope mounted on a pellet rifle.
No. Use only what is printed on the barrel.
Buy a .177 Cleaning rod kit for your air rifle ( If it's a .177 caliber.) DO NOT use any cleaning agents that are used for regular guns, the solvents will ruin the o-rings in the air gun. If it's s break-barrel rifle, break open the barrel slightly ( Don't cock it) and push a clean swab in from the rear of the barrel. Replace the swab several time until you get a clean swab. Do not use any oils on the barrel like 3-n-1. just use Air gun oils like the ones from RWS or Crosman. Wipe the rifle down with a clean rag with a few drops of air gun approved oil. Lubricate the joints with a few drops of Crosman or RWS oil. Clean the rifle about every 1000 shots or sooner if necessary. I would not use any other cleaning oils other than approved Airgun oils See the link below for Air Rifle cleaning kits.
In 1938 the 7.35 Carcano round was introduced, but most were either exported or later refitted back to the 6.5 round, so a Model 91 38 will use one or the other of the 6.5x52 Carcano or 7.35 x 51 Carcano. The barrel should be marked 6.5 or 7.35, but if not, have the barrel slugged.