Multi-pump
Single pump
tank filled
You have many, many options.
Also, for squirrel I'd suggest a .20-.22 caliber rifle. Anything that is .177 caliber and has enough speed to take a squirrel reliably at distance will have a sonic crack.
Put a couple 100 rounds through it, then start buying tins of every type of ammo you can find.
Airguns can be picky, and it may take awhile to figure out what it wants.
Also, go and start studying up on airgun forums and perhaps get a subscription to an airgun magazine.
They are much different than a rimfire or centerfire rifle.
For instance, Due to them having more moving components they are sensative to how you hold them.
If you change your hold, it will change your point of aim.
On small game small changes mean alot.
Much experimentation must be done to learn your airgun.
In the long run it can be a rewarding journey.
BTW, I was friends with an older gentleman who used to hunt pidgins for farmers. He'd kill 500 a year easily, we would talk about his airgun.
I wish I was more into it back then. That's a lot more action that I see hunting anything else, and pellets are cheaper than ammo these days.