From looking at your website, I can get everything that you proposed done in a day (or less).
I build, administer, and update websites daily.
As for your Flash issues, Chrome and other browsers are going away from Flash, and there are other slideshow options available. If you choose me, we can talk about the different solutions to replace your Flash stuff.
With all of my websites, I copy everything to my computer to work on them, create a backup of the original site, perform the updates that is required, and re-upload everything. After the project is complete, I remove the files from my computer, so the only evidence of something done is on the host.
If you have any questions, please feel free to contact me.