The DLC is maybe an hour and a half long if you speed through it. You obviously shouldn't on your first play through.
Most Gators can be avoided which saves Spears for the final boss.
When fighting the first and second bosses use hit and run tactics. Back away from the boss while they attempt to punch you and watch their animations. Once they stop punching and rest rush in for a couple of punches then back off.
The game is vary generous with check points on easy and normal so even if you die you are never far away from where you are going.