The only mod writeup I've ever seen for that blaster is the one I did. I'm not sure it's a great mod, but it exists.
To answer your questions, it's a manual plunger blaster, sometimes called "push-pull" blaster, for obvious reasons. Lately I've seen this style of blaster called HAMPs, after Kane's blaster of that name. I'm not sure about extending the inline clips. I've never seen it done.