Making the move from iMac to rMBP help

Hi

I'm making the move from a 2009 24 inch imac to 13" rMBP due to arrive tomorrow and struggling to get my head round how to adjust to the reduced storage capacity (i plan to sell the iMac).

On my iMac I currently have 151gb free out of 640gb and bought the rMBP with 256 gb storage.

I also have 2 external hard drive, an old La Cie porsche drive (about 8 years old but still going without issue) and a more recent Seagate 3Tb drive - I use the Seagate drive to back up both the contents of the La Cie Drive and also for Time Machine for the iMac.

At the moment the big use of data for the iMac is audio which is using 240 gb, which is backed up both on the La Cie and the Seagate (basically have sold all my CDs and now have all my music only on hard drive and whilst life would still go on without them they are the things I would most like to use and protect)

My confusion is how best to use my hard drives with the rMBP. I would like to use the SSD on the rMBP to run the system and apps/programmes and store videos, media and music etc from the external HDDs. But with it being a laptop I would like to access this without having to be plugged into them.

What I'm confused on is whether I should be using a wireless NSA system and would that work or is it overkill for what I want or whether something like the Toshiba Canvio Wireless Adapter (called the Stor.e Wireless Adapter in UK/EU) http://www.toshiba.com/us/accessories/Storage/Wireless-Storage/HDWW100XKWF1 would work for me?

Has anyone used a wireless disk or wireless disk adaptor and how quick are they? I'm concerned that I will have a very fast computer that is lagging whilst waiting for music or media via a wireless HD.

(I also have an ipad and iphone that it would be nice to be access music and videos from the external hd but def not as important as being to able to access them by rMBP)

Or do I need to buy a 3rd smaller portable HDD external storage to use with the rMBP for music and media? I'm trying to avoid this as I don't want to always have to attach a device to access music.

Or is there a better solution than the above that I'm missing?

Thanks if anyone can advise/help