Hello Fernando,
1. there is no configuration to remove categories block from Home, you can do remove it in code. open template/your_template/tpl/controllers/home.tpl and find area
Code:
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and remove or comment it like below
Code:
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2. It is not possible with default Flynax functions to add seller logo to search form.
You can do it in code also. but it's require changes in few files so i will not post instruction. Send request to tech department - they will do it.