It seems to be a Windows 8.1 issue... Windows 8 and 8.x seem to have many issues with Touchpads.

 

Windows 10 9926 TP

 

In Windows 10 TP I haven't had issues with either. Note the TP isn't perfect there are sometimes issues with the screen rotation.

 

I made a series of tutorial videos in creating recovery media with Dell Backup and Recovery using this system which should be done in advance before upgrading to Windows 10:

 

https://www.youtube.com/playlist?list=PL1RkaknDn7v88-b9HVWAauoWSHDQhoe4w

 

I have made a set of tutorial videos in installing Windows 10:

https://www.youtube.com/playlist?list=PL1RkaknDn7v_SJaBuleIyodZD7Nt_IgqM