Should I go back and do a manual install?

Should I go back and do a manual install?

I’m currently working on a site which i had started on before signing up for wpmudev. This morning at ridiculous o’clock whilst reading through some of the beginner documentation, I read that it’s better to install WP and plugins via an FTP client. It didn't say why it was better. It just is.

Here’s a simple flowchart of what im trying to do with the site:

After a convo with some helpful folks here, I think i should be using :
1. BuddyPress & maybe bbpress?
2. Classifieds plugin
3. Fundraising plugin
4. Multiple themes?

So, I assume everybody here knows more about all this stuff than I do. What do you think? Should I go back and reinstall everything via FTP rather than the bluehost c panel super easy way?

While you’re here, what is your opinion on whether or not i work on the server directly or through the MAMP thing, or on my mac locally , then publishing?

Where should I start?

Please remember, I went to art college and am a graphic designer for a living. I am a white belt in Wordpress. So please don't kick me in the crotch!