I have a Montana...I ordered it from the USA for about €325.It is an excellent GPS and one with which will be easy for you to learn with. The screen is excellent in sunshine and you can transfer tracks that you've ridden on via bluetooth with other same spec models. My camera is gps enabled so I didn't need the 650 with the built in camera.
I will be ordering the mounts this week. I have my RAM mount(ball and socket) up on the bar above my instruments where I find it easier to glance down at rather than look at the crossbar(where you can get a mount for same)
You can buy the RAM mount and rely on batteries or have it charging through a cigar charger via USB. I'd go against this idea as it opens itself for vibration through time and possibly a loose USB plug eventually. Or you can carry a packet of AA batteries once the main battery looses it's charge.
I will be ordering what's called a Rugged Mount which is hard wired from the battery and which charges the gps as you ride, The gps clips into place and can be locked with a small screw if need be.This in turn is bolted to the RAM mount,which is in turn bolted to the moto.
IMHO there's no need to get the TTech mount which,although is a great bit of kit,is just too expensive. It's your call.
I have a 32GB micro SD card in mine which allows me to put maps into it rather than the main 'hard drive' I also use this to store pictures to view(not great quality but OK) of my family whilst on the road.
I use
www.wikiloc.com to download routes,e.g of trails in Spain. Really easy to use once you get the hang of the whole thing.
Here there's a whole post..
http://www.advrider.com/forums/showthread.php?t=688775
So...all that to say take the plunge and enjoy.
.