Need Help with Simpla

Hi. I’ve managed to tweak most things to work how I want, but there’s a few things which I just can’t do with the Simpla theme.

1. Add a search box in the sidebar.

2. Get an Archives page listed under the pages displaying archives by monthly and post only.

3. And this third issue is not such a big deal, but in the recently posted which I managed to get working in the sidebar, is it possible to remove the posts listed that are already visible on the main page? (If that made sense.)

Any help would be greatly appreciated. Thanks in advance!