First point: in project bin -> 3 stipe menu -> zoom, adjust as you like. 

2nd point: "change color when a clip puts on the timeline". for that I change the status on wishlist.

Thanks for your report!

1) It seems you mean the audio / video icon to drag only audio / video to the timeline? If so I don't see why it should be necessary to display them all the time beside to add your second point. (Or do you mean the thumbs it self like @emohr understood???)

2) This seems to be similar to https://bugs.kde.org/show_bug.cgi?id=426861. Personally I like the solution on the other report more.

Please check based on the information above if this report can be closed or at least marked as duplicate. If not please clarify what you meant or how this request differs from the other one.

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
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If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!

This bug has been in NEEDSINFO status with no change for at least
30 days. The bug is now closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!