bruteforce 12 words seed
1) The answer is 12! = 479,001,600 possible mnemonics (less if there are repeated words). Out of these only ~29,937,600 (1 in 16) produce a valid seed. This is definately brute forcable.

2) No, if you want to do this use a longer mnemonic (and make sure you permute them in a truly random way)