How to create a Smartform custom control using javascrip libraries capble to interact with SharePoi

Yes It is possible to using jQuery UI and build control. There are many developers who has build the control. 

I would recommend you to refer K2 Help to buuild control. 

Below is the link to control builder reference.

https://help.k2.com/onlinehelp/k2smartforms/devref/1.0.7/default.htm#k2_smartforms_custom_controls.html

Also there is one developer who developed control and has given pretty good guid on building steps. Below is the link for that

http://codecodecode.ninja/2015/09/building-k2-smartform-control/

I hope this will help you to get started with Custom Control Builder.

Cheers,

VS

Yes. As long as you add resouce files with the project as embaded code. 

The basic thing is the control need its .JS file if interacting with graphics and CSS. once you add those file you can use as reference as embaded. Sometimes control can be slower due to server/client event and execution.