Wow, a lot of questions. First the advantage of the carbine is it's a short light weight rifle that's easy to carry and points quickly. The disadvantage is in .22 it's going to be an adjustable speed model and in .22 cal you're going to want to turn it up and your shot count is going to be low because of the smaller air tube. The plain side lever as you call it is most likely what was called the Classic in the bolt action version and has a larger tube which would give you more shots , but it's a little over a half pound heavier ( feels more) and is not as quick to point . The ERB side lever would give you the most shots per fill but then again , a longer , heavier tube . But even in the ERB version it's lighter than any springer that comes close to the power you'll get out of it. The rifles come with a filler probe that has 1/8" BPT that with Teflon tape mates up with a 1/8" FPT connector on the pump hose. No pins needed when mounting any scope that fits on your PCP. That's another BIG advantage of PCP's , NO RECOIL . No matter which rifle you get , I'm sure you'll be happy with it. Check with Jim at Precisionairguns when you're ready ; if he doesn't have what you want in stock , he'll get it for you. Nice guy to deal with. Very knowledgeable about Air Arm products and you get what you order. kirby