Clean Install Yosemite onto new SSD (Also, what is TRIM?)

Question

Hi,
I've been researching how to replace the Hard Drive on my Late 2011 13inch Macbook Pro (MacBookPro8,1 / 2.4 GHz / Intel Core i5 / SATA III) with a new SSD (maybe a Samsung 840 EVO) and clean install Yosemite onto it. I've found a few ways to do this on the support forums and the macrumors forum, but I want to confirm if I can do it this way:
1. Plug new SSD into the Macbook via a USB cable
2. Download Yosemite onto current Macbook Hard Drive. When I'm prompted to install, chose the new SSD from the list. Complete Installation.
3. Remove old Hard Drive from Macbook and plug new SSD in it's place (and not in the optical bay).
Would this work? I have another external hard drive with all of my documents, pictures and music on which I'm just going to manually remove over, and have no problem doing. I can also download the iLife programs directly from the App Store so I wouldn't be missing out on those either (I do have the iLife '09 discs too). I've also read about creating a bootable USB using DiskMaker X, but I feel the route I outlined would be easier.
Am I missing anything? I do have the EFI Firmware v2.7, so the problems the 2011 MacBooks were having with SATA shouldn't be an issue during this. Also, during my research, I found a references to something called TRIM. Can someone explain TRIM to me?
Thanks,
Steve

Answer 1

Thanks for the response and confirming I can clean install Yosemite onto a new SSD using the process I listed in my initial post.
I have a 13'' MacBook Pro with Yosemite already installed onto it so my graphics card should be set. After almost a month of using it, I haven't noticed any issues on that end.
I guess this TRIM thing is a totally separate subject from this thread. I read Apple is no longer supporting third-party SSD for TRIM support. If you turn it on, but keep a security feature on, you risk your computer not booting correctly. It looks like the only way to have TRIM enabled on a SSD using Yosemite is to have an Apple supplied SSD, or an SSD that can trick Yosemite into thinking it's Apple supplied (like the Angelbird Wrk for Mac SSD).
I've also done a good amount of research that TRIM is only necessary if you're saving a lot of items to the hard drive in one sitting (like photoshop). I primarily use my Mac for Pages (which saves my documents into the cloud now), iTunes and Safari. I guess this would fit me into the "casual user' criteria? I've also read that if you don't use TRIM, your SSD uses "Garbage Collection" (which actually sounds terrible) to keep the SSD informed on what data can be overwritten since it's been deleted by the user. I read that most modern SSD hard drives have a pretty decent Garbage Collection function, so if you leave your computer idle, keep "Put the hard disk(s) to sleep when possible" unchecked, the SSD will run Garbage Collection on it's own and that should be sufficient enough to keep the SSD in good working order.