Regarding Key Strength with DES and Blowfish
I won't say someone would be able to break it 'easily'; however it won't be anywhere as difficult as with a true 128 bit cipher (or even 120 bit cipher; your construction ignores 8 of the key bits).

Here's an outline of how the attack would work: we assume we know the plaintext and the ciphertext, and are trying to recover the key.  When we do is encrypt the plaintext with all $2^{56}$ possible DES keys, and put them in a huge list.  Then, we decrypt the ciphertext will all $2^{64}$ possible Blowfish keys, and put them in another huge list.  Then, we go through the lists, and look for a match; when we find a DES-encrypted ciphertext that matches a Blowfish-decrypted plaintext, that gives us both the DES key and the Blowfish key.

Now, the first obvious objection to this is "if the attacker already knows the plaintext, why does he need the key".  Well, one answer is that this sort of attack can work even if the attacker has a guess of part of the plaintext; if he can just encrypt that region, that is enough to make the attack work.

The second objection is "there's no way anyone has enough memory for lists that big".  While this is true, this attack can be modified to use less memory (at the expense of more computation); in general, if you have $O(2^m)$ memory, this attack can be done in $O(2^{120-m})$ time (for $m \le 56$); this means that if the attacker has a few Terabytes ($2^{40}$ bytes) sitting around, he could do this in $O(2^{80})$ time; that's a bit too close to practical for me