Yes you can implement flash scripts on Wordpress all day long. it’s not a big deal and it’s been done before. You just need to notify that you are better off with a video then a flash image because of SEO reasons.
1.Yes you can easily install the wordpress latest version very easily.
2.its not that hard to install it , just upload the zipped version and extract in the server , it will help in saving lot of time
3.about flash:
last month when i tried to upload some photos in wordpress for sending to my brother .
i failed , i found some problem in attaching ,
so wordpress is not supportig media files sometimes
I think using Wordpress is the best choice in terms of your client’s requirement. You can customize Wordpress to suit your need. If not, you can hire someone to customize for you. Wordpress has many plugins that can makes your life easy.
You can check out the plugins that suits your needs.
How can I tell if a website is a customized Wordpress template? Is there anything in the source code?
In Wordpress blog, what you choose under Appearance - the custom template. Then you know it is customized. Wordpress blog comes with 2 templates - Classic and default.