If I download that wallet file, even though pre release, will I be able to transfer my mined grin into that wallet for safe keeping? Thanks in advance.
you could have your wallet in multiple places. if you want. just use the words to recover your wallet.
I have been using this windows wallet for a few days now and it accepts tx files and http payments. if you keep your wallet on linux and windows, just use the check command in the wallet to keep it updated between the two.