The space issue with updates is a known issue with the 14XX Nuvi line and others. Easy fix, just delete unneeded system files (like the huge library of voice files for virtually every spoken language!) This page does a great job instructing how to open up space on the 2 gig internal storage:
and more importantly, how to do a complete backup of your GPS.
Personally I deleted all the unneeded files and had plenty of room for the most recent map update. Of note, most of the knowledgeable folks advise using the MyGarmin.com dashboard to update lifetime maps, NOT the lifetime map updater which apparently is pretty buggy.
Try that - open up the mygarmin.com/MyDashboard, hook up the GPS, and let the mygarmin plugin find the GPS.
I have an 8gig class 10 (fast!) MicroSD to hold my HUGE junction view file and tons and tons of favorite files. Got it from NewEgg.com (love them) for $7 with free shipping.