In regard to your concern, I would like to inform you that, according to the Datasheet for the Intel® Atom™ Processor Z3700 Series, I was able to confirm that through Display Port 1.1 the maximum resolution supported it is:
2560x1600 pixels on a frequency of 60 Hz. You can confirm this details on the page number 30, under the title 1.4 Difference between SoC SKUs at the following link:
Also, just as a friendly reminder the resolution of 4K works at 4096 x 2160 pixels.
To answer your inquiry; Intel recommends the usage of straight video cables.
The configuration you are trying to setup will require a video adapter (USB to Display port), is not validated by Intel due that it could affect the graphics or you may have no video signal.
If at the end you would like to give it a try and get a third party adapter, make sure the adapter is active (it means it has a separate power source and has a dedicated "chip" that converts the signal from USB to DisplayPort).
About the graphic comparison, between the Intel® Atom™ Processor Z3740 and the Intel® Atom™ Processor Z3735F; at the following link you will be able to see the details under "Graphics Specifications":
Both are Bay Trail generation processors and the difference among them it is that the Z3740 has a Burst frequency of 667.00 MHz; this means that if you are running a game or application that demands a higher process, this one has a little bit more of power.
Also, Z3740 has some additional features like:
-Intel® Quick Sync Video
-Intel® Clear Video HD Technology
-Intel® Wireless Display
**You can find the description of those features at the previous link provided.
That will be the technical and more specific comparison, among both processors.