Modificatiion of Theme – Post and Menu Format

Hi,

We are currently using the Adelle Theme.
We have loaded the Simple Custom CSS plugin.

We would like to modify
a) the header of Posts.
The date that the post is posted is too prominent.
We are using posts to advertise events that occur at some stage in the future, or possibly to refer to a past event.
The post date (in the header) may be interpreted as the event date by some.

We would like to remove the post date from the header.

b) Remove the Search Box from the Main Menu
We would like to remove the Search Box from the Main Menu to leave more room for menu items. We intend to place a Search Box Widget in the Widget sidebar.

c) Change Main Menu background colour
We would like to experiment with something other than a black background for the menu.

Could you advise if any or all of the above changes are possible using a CSS Modification plugin?

If yes, could you provide high level guidelines on how to do this? Whilst I am new to web development, I have programmed for a long time, so I should be able to work it out if I know where to start.

We are also considering changing themes. Do you think that this would be a better alternative?

Cheers,
Graeme