MINIMUM for After Effects and Premiere Pro http://helpx.adobe.com/premiere-pro/system-requirements.html
The program will run... slowly (your external drive needs to be USB3 or eSata for video editing)
https://www.adobe.com/products/premiere.html for the trial to find out for yourself
...your machine is pitifully underpowered and would run extremely slow, ( if at all), with PPro,
Long ago, I started with a dual core laptop which appeared to meet the minimum system requirements as listed on the side of the box....ha ha ha !!...the joke was on ME !!!
Although I managed to get some work done, it ran extremely slow and the experience was PAINFUL !!! Your i3 laptop is not much better than my old dual core machine....you have two more "threads" on the CPU,but, I had a dedicated NVidia GPU where you do not...you only have the "integrated graphics '
At the time, my CPU would ALWAYS be maxxed out at 100% and it could just not handle the load of simple 1080p editing. Your CPU has no "turbo" which increases the CPU frequency when placed under a load. My current laptop has a "base" frequency of 2.4 Ghz which "turbos" up to 3.4 Ghz on all 4 physical cores, ( 8 threads). This allows enough power to smoothly edit 1080p, along with the NVidia 765m GPU.
Try the "trial" version of PPro and see if you can get it to work. Tip : if you only have one drive in the machine, install the program on that boot drive and then either install a second internal SSD for the project files, media, and exports. The cache and media cache files can go on the boot drive....which is hopefully an SSD. If no second 2.5" drive bay.....using an external drive will reduce performance if it is slow. If the laptop has USB 3, a samsung T3 external drive will perform at internal speed over USB3 at speeds of over 400MB read and write per second. If a T1 orT3 drive is too expensive, a couple of years ago Bill an I used particular USB3 thumbdrives which were 128GB capacity and ran over 200MB/sec read and write. Those Patriot thumb drives stopped using the fast memory and became no longer available. Perhaps there are some others around that are cheap and decent performing, ( over 200MB/sec) to allow you to at least see what your machine can do. there have been some improvements in the " integrated GPU" found on your CPU that might help editing. These include H264 encoding and decoding and some other features. Only 8 GB of system memory will hinder performance a bit. Minimum really is 16,but, even that is not great....24GB and above are what is needed.
Good Luck !
As the others have stated, Premiere Pro will render sluggishly on your laptop (if my testing on an older Haswell-generation i5-4210U laptop with only the integrated graphics is any indication). That laptop's i3-7100U CPU and integrated Intel HD 520 graphics is only slightly faster than my laptop's i5-4210U CPU and integrated Intel HD 4400 graphics in Premiere. What's more, 8GB total system RAM is not quite enough RAM for a Premiere Pro-ready system these days.
In addition, if your large external hard drive is only USB 2.0, forget about using it in an editing system completely: The real-life throughput of USB 2.0 is only about 35 MB/second read and 28 MB/second write -- way too slow for today's highly complex codecs these days.