So I previously worked as freelance motiongraphics designer but it was almost impossible to get a full time position so I decided to look elsewhere within "design" circles. After a few months of try I got a graphic/interaction design position at a studio that designs and develops apps for phones and tablets. 

Before starting this job, I had no professional experience designing apps, even though I had a handful of mockup designs and I made it quite clear during my interview. They hired me because they felt I had a good design sense and I also had some other expertise in animation/video that they might need in future. 

I'm a few weeks into my new job and even though I haven't heard any complaints yet I think I'm being far too slow. In my previous works, my workflow was pretty much centered around Aftereffects/Illustrator/3ds max and Cinema 4d. In my current position it's rather Photoshop and Illustrator (my Phtoshop skills is not as sharp as it should be). To make things worse I work solely on a Mac now which adds an extra layer of complexity to everything (shortcuts, workflow etc).

I recently I finished work on my first project and was suppose to deliver graphic assets (over 200 of them) to the developer, it was going to take me a couple of hours but the other designer intervened, asked for the larger versions of the files and used a Photoshop script/plugin to get the over 200 files all in a matter of seconds! Even though I know he has more experience, I couldn't help but feel quite useless. 

My question is, how do I improve my workflow and get things done as quickly as possible? (especially within Photoshop) Does anyone have any tips, plugins, scripts and OSX specific apps that I can use to the things done more quickly. 

My second question is, my other colleague (the other designer), keeps interrupting my work to show me "how things are done", at first I thought he was only being helpful but I'm beginning to get the sense that there is a competitive edge it. Almost every time walks up to my desk to give feedback, he (the other designer) chimes in to give his own thoughts as well. How do I deal with such a person without coming off as a jerk?