If the above two keys are leaked, then your master private key at the account level (m/44'/60'/4') can be back-calculated. That means, any private key (both receiving and change) that you derive from that account is compromised.
To elaborate, BIP 44 uses non-hardened derivation to derive private keys after the account level. The child private key derivation ...
There is a list of BIPs at https://github.com/bitcoin/bips
I don't see anything that specifies a wallet format.
To be honest I'd be surprised to see one. This is something that each implementation ought to determine for itself, Some wallets might use an embedded SQL DBMS, some a Berkely DB format, some a JSON store of some sort and so on. Similarly, the ...
BIP44 is a convention about derivation paths. BIP32 gives you an extended master key which you can then combine with a derivation path to get a private key.
So after you get your master key you are probably looking for the key with derivation path m/44'/0'/0'/0/0. I am not familiar with bitcoinj or Java but from a quick search it seems that you can find ...
Please try the following demo, and the result is same with https://iancoleman.io/bip39/.
$ python3.6 test.py
'mnemonic_words': 'aware report movie exile buyer drum poverty supreme gym oppose float elegant',