Hmm I'm pretty sure I signed up using my browser (not IE, it isn't even an option on my mac), I would have used either Safari or Chrome. Didn't strike any problems with the actual sign-up but I don't believe their cart system was the best I'd come across. I'm based in NZ so was redirected constantly to the Australia-Pacific website. That was annoying because up until a month or so ago the Aussie prices were above the US. Anyhow I took advantage of the reduced prices for the first year and signed up on about the 31st Dec 2012.
Pricing-wise it really does depend on what you use. I'm a multi-user of products so it is a very east choice for me. I use InDesign, Illustrator, Photoshop and Lightroom on a regular basis. I couldn't hope to afford all those at stand alone prices. Feature-wise though I'm not a heavy user and have been happily using CS3 on my work machine for the last year and a half. There are a lot of products in the Suite and they have some nice bonuses if you want to take advantage of them, but they're niche things which not everyone will use or appreciate. The good thing is any updates are brought immediately to the cloud subscribers. If CS moves to CS7 during that time, you get access straight away. Can't really beat that if there's a major upgrade throughout the year.
As for performance, they're much of a muchness if you have a machine that can run them. I'm using a 2011 iMac and they haven't had a problem. The biggest problem is crashes but the Adobe products of late autorecover almost everything so I'm not afraid of losing things. Don't ask me why but they tend to get more stable, I had more crashes early after installation. That may also be to the fact they roll out updates very swiftly too. Is a bit of a pain getting so many but I've got a decent internet connection and the auto-update facility allows you to skip them if you don't want the updates.
As for location of folders, your MAMP should be ok as I think they're defined by MAMP anyway and if you are linking it in with DreamWeaver then that allows for site-specific folders too. Wouldn't anticipate that being an issue but I can't say I've fired up DW for a few years. Can't imagine they've backtracked on that feature as it is pretty basic functionality.