Could you please tell me: Is there a way to store bitcoin on a laptop/ usb drive / mobile without needing a lot of HDD / SD card space ?
I need a wallet / solution file that would not take up space, yet be accessible at (a fairly) short notice
Much love
Then you should avoid BitcoinQT (core wallet) and try MultiBit (multibit.org). It takes only a few seconds to sync and use.
Why ? Does BitcoinQT require to DL the blockchain ?
Yes, BitcoinQT downloads the whole blockchain data, which is usually several GB.
MultiBit is a 'lite' client which downloads most recent block info, but is equally good & secure for most users.
The bitcoin core developers are also working hard to make an "autoprune" feature in it to allow you to run it with a small space usage, though it can't be made in version 0.10.
https://github.com/bitcoin/bitcoin/pull/4701