I wonder why I cannot set time for hotkey for more than 1000 ms.

There's also regression comparing to KDE4., On KDE4 i can press gesture mouse button and release it to see menu, but on Plasma5.3 it's not possible.

Wrong group. In case of the timeout file a bug, it's likely a porting issue (new gui, forgot to adjust the barriers)
For the "regression", i've frankly not even a remote idea what you're talking about

The regression is: I set right mouse button(It open menu in default scenario) to gesture button on KDE4.When I press and release this button, without moving mouse, then menu would appear. This not happen on Plasma5.