Does this amp have a extension speaker jack?

Not really. It has no powered speaker out jack that gets its power from the inboard power out. It has a set of effects in/out stereo jacks that can go to the input of another amp, not an extension speaker unless it's a powered speaker, and XLR jacks that can go to a mixing board, another amp with an XLR input, or a mixing board. If you hook up an ordinary unpowered extension speaker to any of these jacks, you'll get no sound.

Does this amp allow for an active pickup bass?

Absolutely. I’ve got a Fender Deluxe Active Jazz Bass, and they work very well together. Further, there is a very perceptive sound difference when toggling between active and passive, though both modes sound great.

Does this amp require a head, or can i jack in? Can i adjust its settings without an app?

It's fully integrated. Amp, Preamp and Modeling machine all in one. You can adjust settings on the Amp, but I find it easier to change settings using a smart phone, which connects to the amp wirelessly.

Hi, could you tell me the weight and package dimensions?

I'm sorry, but I can't give you the dimensions of the amp in it's shipping carton. I never bothered to check. I was too excited to plug it in and rattle the windows! What I can tell you is this is 800 watts of kick butt amplification, that can be programmed to model specific amp types. I primarily use setting "16," which emulates a big fat Fender Bassman. I play a Hofner 500/1 & a Rick 4001 copy... and the amp just amazing. It weighs 39 pounds. If you don't plan on stacking it in your backline, you can put castors on the bottom & roll it where you need it. It's approx 24 inches tall, 19" wide, with a depth of 14". It's extremely versatile, relatively compact, and has a solid sound. It can rattle your teeth in a small room/stage. I think it's a great value. Hope you enjoy yours.