1. Highly, extremely unlikely, but if it happens, you are now visual, and all the requirements for separation and spacing are on you. An example of how this can go pear shaped is the accident in San Diego with PSA vs Cessna.
2. Advise on your go around; 'bugsmasher flight 1234, going around, we are visual VMC, say instructions' and then follow those instructions. If tower issued the 'cleared for visual' and you accepted, then tower is resp for your nav. Same with appr. Only thing I would caution is if you can't remain VMC, let someone know that you are unable to accept a vector/alt that will put you IMC. Do NOT go IMC without a clearance and readback. You accepted 'visual' flight rules - stick to them(unless contact with ground is imminent, then use your head).